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 final class WP_Hook implements Iterator, ArrayAccess {

    19 

    20 	/**

    21 	 * Hook callbacks.

    22 	 *

    23 	 * @since 4.7.0

    24 	 * @var array

    25 	 */

    26 	public $callbacks = array();

    27 

    28 	/**

    29 	 * The priority keys of actively running iterations of a hook.

    30 	 *

    31 	 * @since 4.7.0

    32 	 * @var array

    33 	 */

    34 	private $iterations = array();

    35 

    36 	/**

    37 	 * The current priority of actively running iterations of a hook.

    38 	 *

    39 	 * @since 4.7.0

    40 	 * @var array

    41 	 */

    42 	private $current_priority = array();

    43 

    44 	/**

    45 	 * Number of levels this hook can be recursively called.

    46 	 *

    47 	 * @since 4.7.0

    48 	 * @var int

    49 	 */

    50 	private $nesting_level = 0;

    51 

    52 	/**

    53 	 * Flag for if we're current doing an action, rather than a filter.

    54 	 *

    55 	 * @since 4.7.0

    56 	 * @var bool

    57 	 */

    58 	private $doing_action = false;

    59 

    60 	/**

    61 	 * Hooks a function or method to a specific filter action.

    62 	 *

    63 	 * @since 4.7.0

    64 	 *

    65 	 * @param string   $tag             The name of the filter to hook the $function_to_add callback to.

    66 	 * @param callable $function_to_add The callback to be run when the filter is applied.

    67 	 * @param int      $priority        The order in which the functions associated with a

    68 	 *                                  particular action are executed. Lower numbers correspond with

    69 	 *                                  earlier execution, and functions with the same priority are executed

    70 	 *                                  in the order in which they were added to the action.

    71 	 * @param int      $accepted_args   The number of arguments the function accepts.

    72 	 */

    73 	public function add_filter( $tag, $function_to_add, $priority, $accepted_args ) {

    74 		$idx = _wp_filter_build_unique_id( $tag, $function_to_add, $priority );

    75 		$priority_existed = isset( $this->callbacks[ $priority ] );

    76 

    77 		$this->callbacks[ $priority ][ $idx ] = array(

    78 			'function' => $function_to_add,

    79 			'accepted_args' => $accepted_args

    80 		);

    81 

    82 		// if we're adding a new priority to the list, put them back in sorted order

    83 		if ( ! $priority_existed && count( $this->callbacks ) > 1 ) {

    84 			ksort( $this->callbacks, SORT_NUMERIC );

    85 		}

    86 

    87 		if ( $this->nesting_level > 0 ) {

    88 			$this->resort_active_iterations( $priority, $priority_existed );

    89 		}

    90 	}

    91 

    92 	/**

    93 	 * Handles reseting callback priority keys mid-iteration.

    94 	 *

    95 	 * @since 4.7.0

    96 	 *

    97 	 * @param bool|int $new_priority     Optional. The priority of the new filter being added. Default false,

    98 	 *                                   for no priority being added.

    99 	 * @param bool     $priority_existed Optional. Flag for whether the priority already existed before the new

   100 	 *                                   filter was added. Default false.

   101 	 */

   102 	private function resort_active_iterations( $new_priority = false, $priority_existed = false ) {

   103 		$new_priorities = array_keys( $this->callbacks );

   104 

   105 		// If there are no remaining hooks, clear out all running iterations.

   106 		if ( ! $new_priorities ) {

   107 			foreach ( $this->iterations as $index => $iteration ) {

   108 				$this->iterations[ $index ] = $new_priorities;

   109 			}

   110 			return;

   111 		}

   112 

   113 		$min = min( $new_priorities );

   114 		foreach ( $this->iterations as $index => &$iteration ) {

   115 			$current = current( $iteration );

   116 			// If we're already at the end of this iteration, just leave the array pointer where it is.

   117 			if ( false === $current ) {

   118 				continue;

   119 			}

   120 

   121 			$iteration = $new_priorities;

   122 

   123 			if ( $current < $min ) {

   124 				array_unshift( $iteration, $current );

   125 				continue;

   126 			}

   127 

   128 			while ( current( $iteration ) < $current ) {

   129 				if ( false === next( $iteration ) ) {

   130 					break;

   131 				}

   132 			}

   133 

   134 			// If we have a new priority that didn't exist, but ::apply_filters() or ::do_action() thinks it's the current priority...

   135 			if ( $new_priority === $this->current_priority[ $index ] && ! $priority_existed ) {

   136 				/*

   137 				 * ... and the new priority is the same as what $this->iterations thinks is the previous

   138 				 * priority, we need to move back to it.

   139 				 */

   140 

   141 				if ( false === current( $iteration ) ) {

   142 					// If we've already moved off the end of the array, go back to the last element.

   143 					$prev = end( $iteration );

   144 				} else {

   145 					// Otherwise, just go back to the previous element.

   146 					$prev = prev( $iteration );

   147 				}

   148 				if ( false === $prev ) {

   149 					// Start of the array. Reset, and go about our day.

   150 					reset( $iteration );

   151 				} elseif ( $new_priority !== $prev ) {

   152 					// Previous wasn't the same. Move forward again.

   153 					next( $iteration );

   154 				}

   155 			}

   156 		}

   157 		unset( $iteration );

   158 	}

   159 

   160 	/**

   161 	 * Unhooks a function or method from a specific filter action.

   162 	 *

   163 	 * @since 4.7.0

   164 	 *

   165 	 * @param string   $tag                The filter hook to which the function to be removed is hooked. Used

   166 	 *                                     for building the callback ID when SPL is not available.

   167 	 * @param callable $function_to_remove The callback to be removed from running when the filter is applied.

   168 	 * @param int      $priority           The exact priority used when adding the original filter callback.

   169 	 * @return bool Whether the callback existed before it was removed.

   170 	 */

   171 	public function remove_filter( $tag, $function_to_remove, $priority ) {

   172 		$function_key = _wp_filter_build_unique_id( $tag, $function_to_remove, $priority );

   173 

   174 		$exists = isset( $this->callbacks[ $priority ][ $function_key ] );

   175 		if ( $exists ) {

   176 			unset( $this->callbacks[ $priority ][ $function_key ] );

   177 			if ( ! $this->callbacks[ $priority ] ) {

   178 				unset( $this->callbacks[ $priority ] );

   179 				if ( $this->nesting_level > 0 ) {

   180 					$this->resort_active_iterations();

   181 				}

   182 			}

   183 		}

   184 		return $exists;

   185 	}

   186 

   187 	/**

   188 	 * Checks if a specific action has been registered for this hook.

   189 	 *

   190 	 * @since 4.7.0

   191 	 *

   192 	 * @param string        $tag               Optional. The name of the filter hook. Used for building

   193 	 *                                         the callback ID when SPL is not available. Default empty.

   194 	 * @param callable|bool $function_to_check Optional. The callback to check for. Default false.

   195 	 * @return bool|int The priority of that hook is returned, or false if the function is not attached.

   196 	 */

   197 	public function has_filter( $tag = '', $function_to_check = false ) {

   198 		if ( false === $function_to_check ) {

   199 			return $this->has_filters();

   200 		}

   201 

   202 		$function_key = _wp_filter_build_unique_id( $tag, $function_to_check, false );

   203 		if ( ! $function_key ) {

   204 			return false;

   205 		}

   206 

   207 		foreach ( $this->callbacks as $priority => $callbacks ) {

   208 			if ( isset( $callbacks[ $function_key ] ) ) {

   209 				return $priority;

   210 			}

   211 		}

   212 

   213 		return false;

   214 	}

   215 

   216 	/**

   217 	 * Checks if any callbacks have been registered for this hook.

   218 	 *

   219 	 * @since 4.7.0

   220 	 *

   221 	 * @return bool True if callbacks have been registered for the current hook, otherwise false.

   222 	 */

   223 	public function has_filters() {

   224 		foreach ( $this->callbacks as $callbacks ) {

   225 			if ( $callbacks ) {

   226 				return true;

   227 			}

   228 		}

   229 		return false;

   230 	}

   231 

   232 	/**

   233 	 * Removes all callbacks from the current filter.

   234 	 *

   235 	 * @since 4.7.0

   236 	 *

   237 	 * @param int|bool $priority Optional. The priority number to remove. Default false.

   238 	 */

   239 	public function remove_all_filters( $priority = false ) {

   240 		if ( ! $this->callbacks ) {

   241 			return;

   242 		}

   243 

   244 		if ( false === $priority ) {

   245 			$this->callbacks = array();

   246 		} else if ( isset( $this->callbacks[ $priority ] ) ) {

   247 			unset( $this->callbacks[ $priority ] );

   248 		}

   249 

   250 		if ( $this->nesting_level > 0 ) {

   251 			$this->resort_active_iterations();

   252 		}

   253 	}

   254 

   255 	/**

   256 	 * Calls the callback functions added to a filter hook.

   257 	 *

   258 	 * @since 4.7.0

   259 	 *

   260 	 * @param mixed $value The value to filter.

   261 	 * @param array $args  Arguments to pass to callbacks.

   262 	 * @return mixed The filtered value after all hooked functions are applied to it.

   263 	 */

   264 	public function apply_filters( $value, $args ) {

   265 		if ( ! $this->callbacks ) {

   266 			return $value;

   267 		}

   268 

   269 		$nesting_level = $this->nesting_level++;

   270 

   271 		$this->iterations[ $nesting_level ] = array_keys( $this->callbacks );

   272 		$num_args = count( $args );

   273 

   274 		do {

   275 			$this->current_priority[ $nesting_level ] = $priority = current( $this->iterations[ $nesting_level ] );

   276 

   277 			foreach ( $this->callbacks[ $priority ] as $the_ ) {

   278 				if( ! $this->doing_action ) {

   279 					$args[ 0 ] = $value;

   280 				}

   281 

   282 				// Avoid the array_slice if possible.

   283 				if ( $the_['accepted_args'] == 0 ) {

   284 					$value = call_user_func_array( $the_['function'], array() );

   285 				} elseif ( $the_['accepted_args'] >= $num_args ) {

   286 					$value = call_user_func_array( $the_['function'], $args );

   287 				} else {

   288 					$value = call_user_func_array( $the_['function'], array_slice( $args, 0, (int)$the_['accepted_args'] ) );

   289 				}

   290 			}

   291 		} while ( false !== next( $this->iterations[ $nesting_level ] ) );

   292 

   293 		unset( $this->iterations[ $nesting_level ] );

   294 		unset( $this->current_priority[ $nesting_level ] );

   295 

   296 		$this->nesting_level--;

   297 

   298 		return $value;

   299 	}

   300 

   301 	/**

   302 	 * Executes the callback functions hooked on a specific action hook.

   303 	 *

   304 	 * @since 4.7.0

   305 	 *

   306 	 * @param mixed $args Arguments to pass to the hook callbacks.

   307 	 */

   308 	public function do_action( $args ) {

   309 		$this->doing_action = true;

   310 		$this->apply_filters( '', $args );

   311 

   312 		// If there are recursive calls to the current action, we haven't finished it until we get to the last one.

   313 		if ( ! $this->nesting_level ) {

   314 			$this->doing_action = false;

   315 		}

   316 	}

   317 

   318 	/**

   319 	 * Processes the functions hooked into the 'all' hook.

   320 	 *

   321 	 * @since 4.7.0

   322 	 *

   323 	 * @param array $args Arguments to pass to the hook callbacks. Passed by reference.

   324 	 */

   325 	public function do_all_hook( &$args ) {

   326 		$nesting_level = $this->nesting_level++;

   327 		$this->iterations[ $nesting_level ] = array_keys( $this->callbacks );

   328 

   329 		do {

   330 			$priority = current( $this->iterations[ $nesting_level ] );

   331 			foreach ( $this->callbacks[ $priority ] as $the_ ) {

   332 				call_user_func_array( $the_['function'], $args );

   333 			}

   334 		} while ( false !== next( $this->iterations[ $nesting_level ] ) );

   335 

   336 		unset( $this->iterations[ $nesting_level ] );

   337 		$this->nesting_level--;

   338 	}

   339 

   340 	/**

   341 	 * Return the current priority level of the currently running iteration of the hook.

   342 	 *

   343 	 * @since 4.7.0

   344 	 *

   345 	 * @return int|false If the hook is running, return the current priority level. If it isn't running, return false.

   346 	 */

   347 	public function current_priority() {

   348 		if ( false === current( $this->iterations ) ) {

   349 			return false;

   350 		}

   351 

   352 		return current( current( $this->iterations ) );

   353 	}

   354 

   355 	/**

   356 	 * Normalizes filters set up before WordPress has initialized to WP_Hook objects.

   357 	 *

   358 	 * @since 4.7.0

   359 	 * @static

   360 	 *

   361 	 * @param array $filters Filters to normalize.

   362 	 * @return WP_Hook[] Array of normalized filters.

   363 	 */

   364 	public static function build_preinitialized_hooks( $filters ) {

   365 		/** @var WP_Hook[] $normalized */

   366 		$normalized = array();

   367 

   368 		foreach ( $filters as $tag => $callback_groups ) {

   369 			if ( is_object( $callback_groups ) && $callback_groups instanceof WP_Hook ) {

   370 				$normalized[ $tag ] = $callback_groups;

   371 				continue;

   372 			}

   373 			$hook = new WP_Hook();

   374 

   375 			// Loop through callback groups.

   376 			foreach ( $callback_groups as $priority => $callbacks ) {

   377 

   378 				// Loop through callbacks.

   379 				foreach ( $callbacks as $cb ) {

   380 					$hook->add_filter( $tag, $cb['function'], $priority, $cb['accepted_args'] );

   381 				}

   382 			}

   383 			$normalized[ $tag ] = $hook;

   384 		}

   385 		return $normalized;

   386 	}

   387 

   388 	/**

   389 	 * Determines whether an offset value exists.

   390 	 *

   391 	 * @since 4.7.0

   392 	 *

   393 	 * @link https://secure.php.net/manual/en/arrayaccess.offsetexists.php

   394 	 *

   395 	 * @param mixed $offset An offset to check for.

   396 	 * @return bool True if the offset exists, false otherwise.

   397 	 */

   398 	public function offsetExists( $offset ) {

   399 		return isset( $this->callbacks[ $offset ] );

   400 	}

   401 

   402 	/**

   403 	 * Retrieves a value at a specified offset.

   404 	 *

   405 	 * @since 4.7.0

   406 	 *

   407 	 * @link https://secure.php.net/manual/en/arrayaccess.offsetget.php

   408 	 *

   409 	 * @param mixed $offset The offset to retrieve.

   410 	 * @return mixed If set, the value at the specified offset, null otherwise.

   411 	 */

   412 	public function offsetGet( $offset ) {

   413 		return isset( $this->callbacks[ $offset ] ) ? $this->callbacks[ $offset ] : null;

   414 	}

   415 

   416 	/**

   417 	 * Sets a value at a specified offset.

   418 	 *

   419 	 * @since 4.7.0

   420 	 *

   421 	 * @link https://secure.php.net/manual/en/arrayaccess.offsetset.php

   422 	 *

   423 	 * @param mixed $offset The offset to assign the value to.

   424 	 * @param mixed $value The value to set.

   425 	 */

   426 	public function offsetSet( $offset, $value ) {

   427 		if ( is_null( $offset ) ) {

   428 			$this->callbacks[] = $value;

   429 		} else {

   430 			$this->callbacks[ $offset ] = $value;

   431 		}

   432 	}

   433 

   434 	/**

   435 	 * Unsets a specified offset.

   436 	 *

   437 	 * @since 4.7.0

   438 	 *

   439 	 * @link https://secure.php.net/manual/en/arrayaccess.offsetunset.php

   440 	 *

   441 	 * @param mixed $offset The offset to unset.

   442 	 */

   443 	public function offsetUnset( $offset ) {

   444 		unset( $this->callbacks[ $offset ] );

   445 	}

   446 

   447 	/**

   448 	 * Returns the current element.

   449 	 *

   450 	 * @since 4.7.0

   451 	 *

   452 	 * @link https://secure.php.net/manual/en/iterator.current.php

   453 	 *

   454 	 * @return array Of callbacks at current priority.

   455 	 */

   456 	public function current() {

   457 		return current( $this->callbacks );

   458 	}

   459 

   460 	/**

   461 	 * Moves forward to the next element.

   462 	 *

   463 	 * @since 4.7.0

   464 	 *

   465 	 * @link https://secure.php.net/manual/en/iterator.next.php

   466 	 *

   467 	 * @return array Of callbacks at next priority.

   468 	 */

   469 	public function next() {

   470 		return next( $this->callbacks );

   471 	}

   472 

   473 	/**

   474 	 * Returns the key of the current element.

   475 	 *

   476 	 * @since 4.7.0

   477 	 *

   478 	 * @link https://secure.php.net/manual/en/iterator.key.php

   479 	 *

   480 	 * @return mixed Returns current priority on success, or NULL on failure

   481 	 */

   482 	public function key() {

   483 		return key( $this->callbacks );

   484 	}

   485 

   486 	/**

   487 	 * Checks if current position is valid.

   488 	 *

   489 	 * @since 4.7.0

   490 	 *

   491 	 * @link https://secure.php.net/manual/en/iterator.valid.php

   492 	 *

   493 	 * @return boolean

   494 	 */

   495 	public function valid() {

   496 		return key( $this->callbacks ) !== null;

   497 	}

   498 

   499 	/**

   500 	 * Rewinds the Iterator to the first element.

   501 	 *

   502 	 * @since 4.7.0

   503 	 *

   504 	 * @link https://secure.php.net/manual/en/iterator.rewind.php

   505 	 */

   506 	public function rewind() {

   507 		reset( $this->callbacks );

   508 	}

   509 

   510 }