<?php
/**
* Installer Hooks Manager
*
* @package Duplicator
* @copyright (c) 2021, Snapcreek LLC
*/
namespace Duplicator\Installer\Core\Hooks;
final class HooksMng
{
/**
*
* @var self
*/
private static $instance = null;
/**
*
* @var Hook[]
*/
private $filters = array();
/**
*
* @var Hook[]
*/
private $actions = array();
/**
*
* @var string[]
*/
private $currentFilter = array();
/**
*
* @return self
*/
public static function getInstance()
{
if (is_null(self::$instance)) {
self::$instance = new self();
}
return self::$instance;
}
/**
* init params and load
*/
private function __construct()
{
}
/**
* Hook a function or method to a specific filter action.
*
* WordPress offers filter hooks to allow plugins to modify
* various types of internal data at runtime.
*
* A plugin can modify data by binding a callback to a filter hook. When the filter
* is later applied, each bound callback is run in order of priority, and given
* the opportunity to modify a value by returning a new value.
*
* The following example shows how a callback function is bound to a filter hook.
*
* Note that `$example` is passed to the callback, (maybe) modified, then returned:
*
* function example_callback( $example ) {
* // Maybe modify $example in some way.
* return $example;
* }
* add_filter( 'example_filter', 'example_callback' );
*
* Bound callbacks can accept from none to the total number of arguments passed as parameters
* in the corresponding applyFilters() call.
*
* In other words, if an applyFilters() call passes four total arguments, callbacks bound to
* it can accept none (the same as 1) of the arguments or up to four. The important part is that
* the `$accepted_args` value must reflect the number of arguments the bound callback *actually*
* opted to accept. If no arguments were accepted by the callback that is considered to be the
* same as accepting 1 argument. For example:
*
* // Filter call.
* $value = applyFilters( 'hook', $value, $arg2, $arg3 );
*
* // Accepting zero/one arguments.
* function example_callback() {
* ...
* return 'some value';
* }
* add_filter( 'hook', 'example_callback' ); // Where $priority is default 10, $accepted_args is default 1.
*
* // Accepting two arguments (three possible).
* function example_callback( $value, $arg2 ) {
* ...
* return $maybe_modified_value;
* }
* add_filter( 'hook', 'example_callback', 10, 2 ); // Where $priority is 10, $accepted_args is 2.
*
* *Note:* The function will return true whether or not the callback is valid.
* It is up to you to take care. This is done for optimization purposes, so
* everything is as quick as possible.
*
* @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 Optional. Used to specify 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. Default 10.
* @param int $accepted_args Optional. The number of arguments the function accepts. Default 1.
*
* @return true
*/
public function addFilter($tag, $function_to_add, $priority = 10, $accepted_args = 1)
{
if (!isset($this->filters[$tag])) {
$this->filters[$tag] = new Hook();
}
$this->filters[$tag]->addFilter($tag, $function_to_add, $priority, $accepted_args);
return true;
}
/**
* Checks if any filter has been registered for a hook.
*
* When using the `$function_to_check` argument, this function may return a non-boolean value
* that evaluates to false (e.g. 0), so use the `===` operator for testing the return value.
*
* @param string $tag The name of the filter hook.
* @param callable|false $function_to_check Optional. The callback to check for. Default false.
*
* @return bool|int If `$function_to_check` is omitted, returns boolean for whether the hook has
* anything registered. When checking a specific function, the priority of that
* hook is returned, or false if the function is not attached.
*/
public function hasFilter($tag, $function_to_check = false)
{
if (!isset($this->filters[$tag])) {
return false;
}
return $this->filters[$tag]->hasFilter($tag, $function_to_check);
}
/**
* Calls the callback functions that have been added to a filter hook.
*
* The callback functions attached to the filter hook are invoked by calling
* this function. This function can be used to create a new filter hook by
* simply calling this function with the name of the new hook specified using
* the `$tag` parameter.
*
* The function also allows for multiple additional arguments to be passed to hooks.
*
* Example usage:
*
* // The filter callback function.
* function example_callback( $string, $arg1, $arg2 ) {
* // (maybe) modify $string.
* return $string;
* }
* add_filter( 'example_filter', 'example_callback', 10, 3 );
*
* /*
* * Apply the filters by calling the 'example_callback()' function
* * that's hooked onto `example_filter` above.
* *
* * - 'example_filter' is the filter hook.
* * - 'filter me' is the value being filtered.
* * - $arg1 and $arg2 are the additional arguments passed to the callback.
* $value = applyFilters( 'example_filter', 'filter me', $arg1, $arg2 );
*
* @param string $tag The name of the filter hook.
* @param mixed $value The value to filter.
* ... $args Additional parameters to pass to the callback functions.
*
* @return mixed The filtered value after all hooked functions are applied to it.
*/
public function applyFilters($tag, $value)
{
$args = func_get_args();
// Do 'all' actions first.
if (isset($this->filters['all'])) {
$this->currentFilter[] = $tag;
$this->callAllHook($args);
}
if (!isset($this->filters[$tag])) {
if (isset($this->filters['all'])) {
array_pop($this->currentFilter);
}
return $value;
}
if (!isset($this->filters['all'])) {
$this->currentFilter[] = $tag;
}
// Don't pass the tag name to Hook.
array_shift($args);
$filtered = $this->filters[$tag]->applyFilters($value, $args);
array_pop($this->currentFilter);
return $filtered;
}
/**
* Removes a function from a specified filter hook.
*
* This function removes a function attached to a specified filter hook. This
* method can be used to remove default functions attached to a specific filter
* hook and possibly replace them with a substitute.
*
* To remove a hook, the $function_to_remove and $priority arguments must match
* when the hook was added. This goes for both filters and actions. No warning
* will be given on removal failure.
*
* @param string $tag The filter hook to which the function to be removed is hooked.
* @param callable $function_to_remove The name of the function which should be removed.
* @param int $priority Optional. The priority of the function. Default 10.
*
* @return bool Whether the function existed before it was removed.
*/
public function removeFilter($tag, $function_to_remove, $priority = 10)
{
$r = false;
if (isset($this->filters[$tag])) {
$r = $this->filters[$tag]->removeFilter($tag, $function_to_remove, $priority);
if (!$this->filters[$tag]->callbacks) {
unset($this->filters[$tag]);
}
}
return $r;
}
/**
* Remove all of the hooks from a filter.
*
* @param string $tag The filter to remove hooks from.
* @param int|false $priority Optional. The priority number to remove. Default false.
*
* @return true True when finished.
*/
public function removeAllFilters($tag, $priority = false)
{
if (isset($this->filters[$tag])) {
$this->filters[$tag]->removeAllFilters($priority);
if (!$this->filters[$tag]->hasFilters()) {
unset($this->filters[$tag]);
}
}
return true;
}
/**
* Hooks a function on to a specific action.
*
* Actions are the hooks that the WordPress core launches at specific points
* during execution, or when specific events occur. Plugins can specify that
* one or more of its PHP functions are executed at these points, using the
* Action API.
*
* @param string $tag The name of the action to which the $function_to_add is hooked.
* @param callable $function_to_add The name of the function you wish to be called.
* @param int $priority Optional. Used to specify the order in which the functions
* associated with a particular action are executed. Default 10.
* 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 $accepted_args Optional. The number of arguments the function accepts. Default 1.
*
* @return true Will always return true.
*/
public function addAction($tag, $function_to_add, $priority = 10, $accepted_args = 1)
{
return $this->addFilter($tag, $function_to_add, $priority, $accepted_args);
}
/**
* Execute functions hooked on a specific action hook.
*
* This function invokes all functions attached to action hook `$tag`. It is
* possible to create new action hooks by simply calling this function,
* specifying the name of the new hook using the `$tag` parameter.
*
* You can pass extra arguments to the hooks, much like you can with `applyFilters()`.
*
* Example usage:
*
* // The action callback function.
* function example_callback( $arg1, $arg2 ) {
* // (maybe) do something with the args.
* }
* add_action( 'example_action', 'example_callback', 10, 2 );
*
* /*
* * Trigger the actions by calling the 'example_callback()' function
* * that's hooked onto `example_action` above.
* *
* * - 'example_action' is the action hook.
* * - $arg1 and $arg2 are the additional arguments passed to the callback.
* $value = do_action( 'example_action', $arg1, $arg2 );
*
* @global Hook[] $this->filters Stores all of the filters and actions.
* @global string[] $this->currentFilter Stores the list of current filters with the current one last.
*
* @param string $tag The name of the action to be executed.
* ...$arg Optional. Additional arguments which are passed on to the
* functions hooked to the action. Default empty.
*
* @return void
*/
public function doAction($tag)
{
$arg = $all_args = func_get_args();
array_shift($arg); // remove tag action
// Do 'all' actions first.
if (isset($this->filters['all'])) {
$this->currentFilter[] = $tag;
$this->callAllHook($all_args);
}
if (!isset($this->filters[$tag])) {
if (isset($this->filters['all'])) {
array_pop($this->currentFilter);
}
return;
}
if (!isset($this->filters['all'])) {
$this->currentFilter[] = $tag;
}
if (empty($arg)) {
$arg[] = '';
} elseif (is_array($arg[0]) && 1 === count($arg[0]) && isset($arg[0][0]) && is_object($arg[0][0])) {
// Backward compatibility for PHP4-style passing of `array( &$this )` as action `$arg`.
$arg[0] = $arg[0][0];
}
$this->filters[$tag]->doAction($arg);
array_pop($this->currentFilter);
}
/**
* Checks if any action has been registered for a hook.
*
* When using the `$function_to_check` argument, this function may return a non-boolean value
* that evaluates to false (e.g. 0), so use the `===` operator for testing the return value.
*
* @see hasFilter() has_action() is an alias of hasFilter().
*
* @param string $tag The name of the action hook.
* @param callable|false $function_to_check Optional. The callback to check for. Default false.
*
* @return bool|int If `$function_to_check` is omitted, returns boolean for whether the hook has
* anything registered. When checking a specific function, the priority of that
* hook is returned, or false if the function is not attached.
*/
public function hasAction($tag, $function_to_check = false)
{
return $this->hasFilter($tag, $function_to_check);
}
/**
* Removes a function from a specified action hook.
*
* This function removes a function attached to a specified action hook. This
* method can be used to remove default functions attached to a specific filter
* hook and possibly replace them with a substitute.
*
* @param string $tag The action hook to which the function to be removed is hooked.
* @param callable $function_to_remove The name of the function which should be removed.
* @param int $priority Optional. The priority of the function. Default 10.
*
* @return bool Whether the function is removed.
*/
public function removeAction($tag, $function_to_remove, $priority = 10)
{
return $this->removeFilter($tag, $function_to_remove, $priority);
}
/**
* Remove all of the hooks from an action.
*
* @param string $tag The action to remove hooks from.
* @param int|false $priority The priority number to remove them from. Default false.
*
* @return true True when finished.
*/
public function removeAllActions($tag, $priority = false)
{
return $this->removeAllFilters($tag, $priority);
}
/**
* Retrieve the name of the current filter or action.
*
* @global string[] $wp_current_filter Stores the list of current filters with the current one last
*
* @return string Hook name of the current filter or action.
*/
public function currentFilter()
{
return end($this->currentFilter);
}
/**
* Retrieve the name of the current action.
*
* @return string Hook name of the current action.
*/
public function currentAction()
{
return $this->currentFilter();
}
/**
* Call the 'all' hook, which will process the functions hooked into it.
*
* The 'all' hook passes all of the arguments or parameters that were used for
* the hook, which this function was called for.
*
* This function is used internally for apply_filters(), do_action(), and
* do_action_ref_array() and is not meant to be used from outside those
* functions. This function does not check for the existence of the all hook, so
* it will fail unless the all hook exists prior to this function call.
*
* @global Hook[] $this->filters Stores all of the filters and actions.
*
* @param array $args The collected parameters from the hook that was called.
*
* @return void
*/
private function callAllHook($args)
{
$this->filters['all']->doAllHook($args);
}
}
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