· 6 years ago · Oct 16, 2019, 04:32 PM
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 */
18final 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 } elseif ( 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 *
360 * @param array $filters Filters to normalize.
361 * @return WP_Hook[] Array of normalized filters.
362 */
363 public static function build_preinitialized_hooks( $filters ) {
364 /** @var WP_Hook[] $normalized */
365 $normalized = array();
366
367 foreach ( $filters as $tag => $callback_groups ) {
368 if ( is_object( $callback_groups ) && $callback_groups instanceof WP_Hook ) {
369 $normalized[ $tag ] = $callback_groups;
370 continue;
371 }
372 $hook = new WP_Hook();
373
374 // Loop through callback groups.
375 foreach ( $callback_groups as $priority => $callbacks ) {
376
377 // Loop through callbacks.
378 foreach ( $callbacks as $cb ) {
379 $hook->add_filter( $tag, $cb['function'], $priority, $cb['accepted_args'] );
380 }
381 }
382 $normalized[ $tag ] = $hook;
383 }
384 return $normalized;
385 }
386
387 /**
388 * Determines whether an offset value exists.
389 *
390 * @since 4.7.0
391 *
392 * @link https://secure.php.net/manual/en/arrayaccess.offsetexists.php
393 *
394 * @param mixed $offset An offset to check for.
395 * @return bool True if the offset exists, false otherwise.
396 */
397 public function offsetExists( $offset ) {
398 return isset( $this->callbacks[ $offset ] );
399 }
400
401 /**
402 * Retrieves a value at a specified offset.
403 *
404 * @since 4.7.0
405 *
406 * @link https://secure.php.net/manual/en/arrayaccess.offsetget.php
407 *
408 * @param mixed $offset The offset to retrieve.
409 * @return mixed If set, the value at the specified offset, null otherwise.
410 */
411 public function offsetGet( $offset ) {
412 return isset( $this->callbacks[ $offset ] ) ? $this->callbacks[ $offset ] : null;
413 }
414
415 /**
416 * Sets a value at a specified offset.
417 *
418 * @since 4.7.0
419 *
420 * @link https://secure.php.net/manual/en/arrayaccess.offsetset.php
421 *
422 * @param mixed $offset The offset to assign the value to.
423 * @param mixed $value The value to set.
424 */
425 public function offsetSet( $offset, $value ) {
426 if ( is_null( $offset ) ) {
427 $this->callbacks[] = $value;
428 } else {
429 $this->callbacks[ $offset ] = $value;
430 }
431 }
432
433 /**
434 * Unsets a specified offset.
435 *
436 * @since 4.7.0
437 *
438 * @link https://secure.php.net/manual/en/arrayaccess.offsetunset.php
439 *
440 * @param mixed $offset The offset to unset.
441 */
442 public function offsetUnset( $offset ) {
443 unset( $this->callbacks[ $offset ] );
444 }
445
446 /**
447 * Returns the current element.
448 *
449 * @since 4.7.0
450 *
451 * @link https://secure.php.net/manual/en/iterator.current.php
452 *
453 * @return array Of callbacks at current priority.
454 */
455 public function current() {
456 return current( $this->callbacks );
457 }
458
459 /**
460 * Moves forward to the next element.
461 *
462 * @since 4.7.0
463 *
464 * @link https://secure.php.net/manual/en/iterator.next.php
465 *
466 * @return array Of callbacks at next priority.
467 */
468 public function next() {
469 return next( $this->callbacks );
470 }
471
472 /**
473 * Returns the key of the current element.
474 *
475 * @since 4.7.0
476 *
477 * @link https://secure.php.net/manual/en/iterator.key.php
478 *
479 * @return mixed Returns current priority on success, or NULL on failure
480 */
481 public function key() {
482 return key( $this->callbacks );
483 }
484
485 /**
486 * Checks if current position is valid.
487 *
488 * @since 4.7.0
489 *
490 * @link https://secure.php.net/manual/en/iterator.valid.php
491 *
492 * @return boolean
493 */
494 public function valid() {
495 return key( $this->callbacks ) !== null;
496 }
497
498 /**
499 * Rewinds the Iterator to the first element.
500 *
501 * @since 4.7.0
502 *
503 * @link https://secure.php.net/manual/en/iterator.rewind.php
504 */
505 public function rewind() {
506 reset( $this->callbacks );
507 }
508
509}