--- /dev/null
+<?php
+/**
+ * Plugin API: WP_Hook class
+ *
+ * @package WordPress
+ * @subpackage Plugin
+ * @since 4.7.0
+ */
+
+/**
+ * Core class used to implement action and filter hook functionality.
+ *
+ * @since 4.7.0
+ *
+ * @see Iterator
+ * @see ArrayAccess
+ */
+final class WP_Hook implements Iterator, ArrayAccess {
+
+ /**
+ * Hook callbacks.
+ *
+ * @since 4.7.0
+ * @access public
+ * @var array
+ */
+ public $callbacks = array();
+
+ /**
+ * The priority keys of actively running iterations of a hook.
+ *
+ * @since 4.7.0
+ * @access private
+ * @var array
+ */
+ private $iterations = array();
+
+ /**
+ * The current priority of actively running iterations of a hook.
+ *
+ * @since 4.7.0
+ * @access private
+ * @var array
+ */
+ private $current_priority = array();
+
+ /**
+ * Number of levels this hook can be recursively called.
+ *
+ * @since 4.7.0
+ * @access private
+ * @var int
+ */
+ private $nesting_level = 0;
+
+ /**
+ * Flag for if we're current doing an action, rather than a filter.
+ *
+ * @since 4.7.0
+ * @access private
+ * @var bool
+ */
+ private $doing_action = false;
+
+ /**
+ * Hooks a function or method to a specific filter action.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @param string $tag The name of the filter to hook the $function_to_add callback to.
+ * @param callable $function_to_add The callback to be run when the filter is applied.
+ * @param int $priority The order in which the functions associated with a
+ * particular action are executed. 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.
+ * @param int $accepted_args The number of arguments the function accepts.
+ */
+ public function add_filter( $tag, $function_to_add, $priority, $accepted_args ) {
+ $idx = _wp_filter_build_unique_id( $tag, $function_to_add, $priority );
+ $priority_existed = isset( $this->callbacks[ $priority ] );
+
+ $this->callbacks[ $priority ][ $idx ] = array(
+ 'function' => $function_to_add,
+ 'accepted_args' => $accepted_args
+ );
+
+ // if we're adding a new priority to the list, put them back in sorted order
+ if ( ! $priority_existed && count( $this->callbacks ) > 1 ) {
+ ksort( $this->callbacks, SORT_NUMERIC );
+ }
+
+ if ( $this->nesting_level > 0 ) {
+ $this->resort_active_iterations( $priority, $priority_existed );
+ }
+ }
+
+ /**
+ * Handles reseting callback priority keys mid-iteration.
+ *
+ * @since 4.7.0
+ * @access private
+ *
+ * @param bool|int $new_priority Optional. The priority of the new filter being added. Default false,
+ * for no priority being added.
+ * @param bool $priority_existed Optional. Flag for whether the priority already existed before the new
+ * filter was added. Default false.
+ */
+ private function resort_active_iterations( $new_priority = false, $priority_existed = false ) {
+ $new_priorities = array_keys( $this->callbacks );
+
+ // If there are no remaining hooks, clear out all running iterations.
+ if ( ! $new_priorities ) {
+ foreach ( $this->iterations as $index => $iteration ) {
+ $this->iterations[ $index ] = $new_priorities;
+ }
+ return;
+ }
+
+ $min = min( $new_priorities );
+ foreach ( $this->iterations as $index => &$iteration ) {
+ $current = current( $iteration );
+ // If we're already at the end of this iteration, just leave the array pointer where it is.
+ if ( false === $current ) {
+ continue;
+ }
+
+ $iteration = $new_priorities;
+
+ if ( $current < $min ) {
+ array_unshift( $iteration, $current );
+ continue;
+ }
+
+ while ( current( $iteration ) < $current ) {
+ if ( false === next( $iteration ) ) {
+ break;
+ }
+ }
+
+ // If we have a new priority that didn't exist, but ::apply_filters() or ::do_action() thinks it's the current priority...
+ if ( $new_priority === $this->current_priority[ $index ] && ! $priority_existed ) {
+ /*
+ * ... and the new priority is the same as what $this->iterations thinks is the previous
+ * priority, we need to move back to it.
+ */
+
+ if ( false === current( $iteration ) ) {
+ // If we've already moved off the end of the array, go back to the last element.
+ $prev = end( $iteration );
+ } else {
+ // Otherwise, just go back to the previous element.
+ $prev = prev( $iteration );
+ }
+ if ( false === $prev ) {
+ // Start of the array. Reset, and go about our day.
+ reset( $iteration );
+ } elseif ( $new_priority !== $prev ) {
+ // Previous wasn't the same. Move forward again.
+ next( $iteration );
+ }
+ }
+ }
+ unset( $iteration );
+ }
+
+ /**
+ * Unhooks a function or method from a specific filter action.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @param string $tag The filter hook to which the function to be removed is hooked. Used
+ * for building the callback ID when SPL is not available.
+ * @param callable $function_to_remove The callback to be removed from running when the filter is applied.
+ * @param int $priority The exact priority used when adding the original filter callback.
+ * @return bool Whether the callback existed before it was removed.
+ */
+ public function remove_filter( $tag, $function_to_remove, $priority ) {
+ $function_key = _wp_filter_build_unique_id( $tag, $function_to_remove, $priority );
+
+ $exists = isset( $this->callbacks[ $priority ][ $function_key ] );
+ if ( $exists ) {
+ unset( $this->callbacks[ $priority ][ $function_key ] );
+ if ( ! $this->callbacks[ $priority ] ) {
+ unset( $this->callbacks[ $priority ] );
+ if ( $this->nesting_level > 0 ) {
+ $this->resort_active_iterations();
+ }
+ }
+ }
+ return $exists;
+ }
+
+ /**
+ * Checks if a specific action has been registered for this hook.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @param callable|bool $function_to_check Optional. The callback to check for. Default false.
+ * @param string $tag Optional. The name of the filter hook. Used for building
+ * the callback ID when SPL is not available. Default empty.
+ * @return bool|int The priority of that hook is returned, or false if the function is not attached.
+ */
+ public function has_filter( $tag = '', $function_to_check = false ) {
+ if ( false === $function_to_check ) {
+ return $this->has_filters();
+ }
+
+ $function_key = _wp_filter_build_unique_id( $tag, $function_to_check, false );
+ if ( ! $function_key ) {
+ return false;
+ }
+
+ foreach ( $this->callbacks as $priority => $callbacks ) {
+ if ( isset( $callbacks[ $function_key ] ) ) {
+ return $priority;
+ }
+ }
+
+ return false;
+ }
+
+ /**
+ * Checks if any callbacks have been registered for this hook.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @return bool True if callbacks have been registered for the current hook, otherwise false.
+ */
+ public function has_filters() {
+ foreach ( $this->callbacks as $callbacks ) {
+ if ( $callbacks ) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /**
+ * Removes all callbacks from the current filter.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @param int|bool $priority Optional. The priority number to remove. Default false.
+ */
+ public function remove_all_filters( $priority = false ) {
+ if ( ! $this->callbacks ) {
+ return;
+ }
+
+ if ( false === $priority ) {
+ $this->callbacks = array();
+ } else if ( isset( $this->callbacks[ $priority ] ) ) {
+ unset( $this->callbacks[ $priority ] );
+ }
+
+ if ( $this->nesting_level > 0 ) {
+ $this->resort_active_iterations();
+ }
+ }
+
+ /**
+ * Calls the callback functions added to a filter hook.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @param mixed $value The value to filter.
+ * @param array $args Arguments to pass to callbacks.
+ * @return mixed The filtered value after all hooked functions are applied to it.
+ */
+ public function apply_filters( $value, $args ) {
+ if ( ! $this->callbacks ) {
+ return $value;
+ }
+
+ $nesting_level = $this->nesting_level++;
+
+ $this->iterations[ $nesting_level ] = array_keys( $this->callbacks );
+ $num_args = count( $args );
+
+ do {
+ $this->current_priority[ $nesting_level ] = $priority = current( $this->iterations[ $nesting_level ] );
+
+ foreach ( $this->callbacks[ $priority ] as $the_ ) {
+ if( ! $this->doing_action ) {
+ $args[ 0 ] = $value;
+ }
+
+ // Avoid the array_slice if possible.
+ if ( $the_['accepted_args'] == 0 ) {
+ $value = call_user_func_array( $the_['function'], array() );
+ } elseif ( $the_['accepted_args'] >= $num_args ) {
+ $value = call_user_func_array( $the_['function'], $args );
+ } else {
+ $value = call_user_func_array( $the_['function'], array_slice( $args, 0, (int)$the_['accepted_args'] ) );
+ }
+ }
+ } while ( false !== next( $this->iterations[ $nesting_level ] ) );
+
+ unset( $this->iterations[ $nesting_level ] );
+ unset( $this->current_priority[ $nesting_level ] );
+
+ $this->nesting_level--;
+
+ return $value;
+ }
+
+ /**
+ * Executes the callback functions hooked on a specific action hook.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @param mixed $args Arguments to pass to the hook callbacks.
+ */
+ public function do_action( $args ) {
+ $this->doing_action = true;
+ $this->apply_filters( '', $args );
+
+ // If there are recursive calls to the current action, we haven't finished it until we get to the last one.
+ if ( ! $this->nesting_level ) {
+ $this->doing_action = false;
+ }
+ }
+
+ /**
+ * Processes the functions hooked into the 'all' hook.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @param array $args Arguments to pass to the hook callbacks. Passed by reference.
+ */
+ public function do_all_hook( &$args ) {
+ $nesting_level = $this->nesting_level++;
+ $this->iterations[ $nesting_level ] = array_keys( $this->callbacks );
+
+ do {
+ $priority = current( $this->iterations[ $nesting_level ] );
+ foreach ( $this->callbacks[ $priority ] as $the_ ) {
+ call_user_func_array( $the_['function'], $args );
+ }
+ } while ( false !== next( $this->iterations[ $nesting_level ] ) );
+
+ unset( $this->iterations[ $nesting_level ] );
+ $this->nesting_level--;
+ }
+
+ /**
+ * Return the current priority level of the currently running iteration of the hook.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @return int|false If the hook is running, return the current priority level. If it isn't running, return false.
+ */
+ public function current_priority() {
+ if ( false === current( $this->iterations ) ) {
+ return false;
+ }
+
+ return current( current( $this->iterations ) );
+ }
+
+ /**
+ * Normalizes filters set up before WordPress has initialized to WP_Hook objects.
+ *
+ * @since 4.7.0
+ * @access public
+ * @static
+ *
+ * @param array $filters Filters to normalize.
+ * @return WP_Hook[] Array of normalized filters.
+ */
+ public static function build_preinitialized_hooks( $filters ) {
+ /** @var WP_Hook[] $normalized */
+ $normalized = array();
+
+ foreach ( $filters as $tag => $callback_groups ) {
+ if ( is_object( $callback_groups ) && $callback_groups instanceof WP_Hook ) {
+ $normalized[ $tag ] = $callback_groups;
+ continue;
+ }
+ $hook = new WP_Hook();
+
+ // Loop through callback groups.
+ foreach ( $callback_groups as $priority => $callbacks ) {
+
+ // Loop through callbacks.
+ foreach ( $callbacks as $cb ) {
+ $hook->add_filter( $tag, $cb['function'], $priority, $cb['accepted_args'] );
+ }
+ }
+ $normalized[ $tag ] = $hook;
+ }
+ return $normalized;
+ }
+
+ /**
+ * Determines whether an offset value exists.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/arrayaccess.offsetexists.php
+ *
+ * @param mixed $offset An offset to check for.
+ * @return bool True if the offset exists, false otherwise.
+ */
+ public function offsetExists( $offset ) {
+ return isset( $this->callbacks[ $offset ] );
+ }
+
+ /**
+ * Retrieves a value at a specified offset.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/arrayaccess.offsetget.php
+ *
+ * @param mixed $offset The offset to retrieve.
+ * @return mixed If set, the value at the specified offset, null otherwise.
+ */
+ public function offsetGet( $offset ) {
+ return isset( $this->callbacks[ $offset ] ) ? $this->callbacks[ $offset ] : null;
+ }
+
+ /**
+ * Sets a value at a specified offset.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/arrayaccess.offsetset.php
+ *
+ * @param mixed $offset The offset to assign the value to.
+ * @param mixed $value The value to set.
+ */
+ public function offsetSet( $offset, $value ) {
+ if ( is_null( $offset ) ) {
+ $this->callbacks[] = $value;
+ } else {
+ $this->callbacks[ $offset ] = $value;
+ }
+ }
+
+ /**
+ * Unsets a specified offset.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/arrayaccess.offsetunset.php
+ *
+ * @param mixed $offset The offset to unset.
+ */
+ public function offsetUnset( $offset ) {
+ unset( $this->callbacks[ $offset ] );
+ }
+
+ /**
+ * Returns the current element.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/iterator.current.php
+ *
+ * @return array Of callbacks at current priority.
+ */
+ public function current() {
+ return current( $this->callbacks );
+ }
+
+ /**
+ * Moves forward to the next element.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/iterator.next.php
+ *
+ * @return array Of callbacks at next priority.
+ */
+ public function next() {
+ return next( $this->callbacks );
+ }
+
+ /**
+ * Returns the key of the current element.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/iterator.key.php
+ *
+ * @return mixed Returns current priority on success, or NULL on failure
+ */
+ public function key() {
+ return key( $this->callbacks );
+ }
+
+ /**
+ * Checks if current position is valid.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/iterator.valid.php
+ *
+ * @return boolean
+ */
+ public function valid() {
+ return key( $this->callbacks ) !== null;
+ }
+
+ /**
+ * Rewinds the Iterator to the first element.
+ *
+ * @since 4.7.0
+ * @access public
+ *
+ * @link http://php.net/manual/en/iterator.rewind.php
+ */
+ public function rewind() {
+ reset( $this->callbacks );
+ }
+
+}
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