WordPress/wp-includes/plugin.php

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<?php
/**
* Hooks a function to a specific filter action.
*
* Filters are the hooks that WordPress launches to modify text of various types
* before adding it to the database or sending it to the browser screen. Plugins
* can specify that one or more of its PHP functions is executed to
* modify specific types of text at these times, using the Filter API.
* See the [Plugin API] for a list of filter hooks.
*
* @param string $tag The name of the filter to hook the <tt>$function_to_add</tt> to.
* @param callback $function_to_add The name of the function to be called 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 (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 $accepted_args optional. The number of arguments the function accept (default 1). In WordPress 1.5.1+, hooked functions can take extra arguments that are set when the matching do_action() or apply_filters() call is run.
* @return boolean true if the <tt>$function_to_add</tt> is added succesfully to filter <tt>$tag</tt>. How many arguments your function takes. In WordPress 1.5.1+, hooked functions can take extra arguments that are set when the matching <tt>do_action()</tt> or <tt>apply_filters()</tt> call is run. For example, the action <tt>comment_id_not_found</tt> will pass any functions that hook onto it the ID of the requested comment.
*/
function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
global $wp_filter, $merged_filters;
// So the format is wp_filter['tag']['array of priorities']['array of functions serialized']['array of ['array (functions, accepted_args)]']
$wp_filter[$tag][$priority][serialize($function_to_add)] = array('function' => $function_to_add, 'accepted_args' => $accepted_args);
unset( $merged_filters[ $tag ] );
return true;
}
/**
* Call the functions added to a filter hook.
*
* The callback functions attached to filter hook <tt>$tag</tt> 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 <tt>$tag</a> parameter.
* @uses merge_filters Merges the filter hooks using this function.
* @param string $tag The name of the filter hook.
* @param string $string The text on which the filters hooked to <tt>$tag</tt> are applied on.
* @param mixed $var,... Additional variables passed to the functions hooked to <tt>$tag</tt>.
* @return string The text in <tt>$string</tt> after all hooked functions are applied to it.
*/
function apply_filters($tag, $string) {
global $wp_filter, $merged_filters;
if ( !isset( $merged_filters[ $tag ] ) )
merge_filters($tag);
if ( !isset($wp_filter[$tag]) )
return $string;
reset( $wp_filter[ $tag ] );
$args = func_get_args();
do{
foreach( (array) current($wp_filter[$tag]) as $the_ )
if ( !is_null($the_['function']) ){
$args[1] = $string;
$string = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args']));
}
} while ( next($wp_filter[$tag]) !== false );
return $string;
}
/**
* Merge the filter functions of a specific filter hook with generic filter functions.
*
* It is possible to defined generic filter functions using the filter hook
* <em>all</e>. These functions are called for every filter tag. This function
* merges the functions attached to the <em>all</em> hook with the functions
* of a specific hoook defined by <tt>$tag</tt>.
* @param string $tag The filter hook of which the functions should be merged.
*/
function merge_filters($tag) {
global $wp_filter, $merged_filters;
if ( isset($wp_filter['all']) && is_array($wp_filter['all']) )
$wp_filter[$tag] = array_merge($wp_filter['all'], (array) $wp_filter[$tag]);
if ( isset($wp_filter[$tag]) ){
reset($wp_filter[$tag]);
uksort($wp_filter[$tag], "strnatcasecmp");
}
$merged_filters[ $tag ] = true;
}
/**
* 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.
* @param string $tag The filter hook to which the function to be removed is hooked.
* @param callback $function_to_remove The name of the function which should be removed.
* @param int $priority optional. The priority of the function (default: 10).
* @param int $accepted_args optional. The number of arguments the function accpets (default: 1).
* @return boolean Whether the function is removed.
*/
function remove_filter($tag, $function_to_remove, $priority = 10, $accepted_args = 1) {
$function_to_remove = serialize($function_to_remove);
$r = isset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]);
unset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]);
unset($GLOBALS['merged_filters'][$tag]);
return $r;
}
/**
* 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 $tag The name of the action to which the <tt>$function_to-add</tt> is hooked.
* @param callback $function_to_add The name of the function you wish to be called. Note: any of the syntaxes explained in the PHP documentation for the 'callback' type (http://us2.php.net/manual/en/language.pseudo-types.php#language.types.callback) are valid.
* @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 $accepted_args optional. The number of arguments the function accept (default 1). In WordPress 1.5.1+, hooked functions can take extra arguments that are set when the matching do_action() or apply_filters() call is run.
* @return boolean Always true.
*/
function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
add_filter($tag, $function_to_add, $priority, $accepted_args);
}
/**
* Execute functions hooked on a specific action hook.
*
* This function invokes all functions attached to action hook <tt>$tag</tt>.
* It is possible to create new action hooks by simply calling this function,
* specifying the name of the new hook using the <tt>$tag</tt> parameter.
* @uses merge_filters
* @param string $tag The name of the action to be executed.
* @param mixed $arg,... Optional additional arguments which are passed on to the functions hooked to the action.
*/
function do_action($tag, $arg = '') {
global $wp_filter, $wp_actions;
if ( is_array($wp_actions) )
$wp_actions[] = $tag;
else
$wp_actions = array($tag);
$args = array();
if ( is_array($arg) && 1 == count($arg) && is_object($arg[0]) ) // array(&$this)
$args[] =& $arg[0];
else
$args[] = $arg;
for ( $a = 2; $a < func_num_args(); $a++ )
$args[] = func_get_arg($a);
merge_filters($tag);
if ( !isset($wp_filter[$tag]) )
return;
do{
foreach( (array) current($wp_filter[$tag]) as $the_ )
if ( !is_null($the_['function']) )
call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
} while ( next($wp_filter[$tag]) !== false );
}
/**
* Return the number times an action is fired.
* @param string $tag The name of the action hook.
* @return int The number of times action hook <tt>$tag</tt> is fired
*/
function did_action($tag) {
global $wp_actions;
if ( empty($wp_actions) )
return 0;
return count(array_keys($wp_actions, $tag));
}
/**
* Execute functions hooked on a specific action hook, specifying arguments in a array.
*
* This function is identical to {@link do_action}, but the argumetns passe to
* the functions hooked to <tt>$tag</tt> are supplied using an array.
* @param string $tag The name of the action to be executed.
* @param array $args The arguments supplied to the functions hooked to <tt>$tag</tt>
*/
function do_action_ref_array($tag, $args) {
global $wp_filter, $wp_actions;
if ( !is_array($wp_actions) )
$wp_actions = array($tag);
else
$wp_actions[] = $tag;
merge_filters($tag);
if ( !isset($wp_filter[$tag]) )
return;
do{
foreach( (array) current($wp_filter[$tag]) as $the_ )
if ( !is_null($the_['function']) )
call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
} while ( next($wp_filter[$tag]) );
}
/**
* 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 callback $function_to_remove The name of the function which should be removed.
* @param int $priority optional The priority of the function (default: 10).
* @param int $accepted_args optional. The number of arguments the function accpets (default: 1).
* @return boolean Whether the function is removed.
*/
function remove_action($tag, $function_to_remove, $priority = 10, $accepted_args = 1) {
return remove_filter($tag, $function_to_remove, $priority, $accepted_args);
}
//
// Functions for handling plugins.
//
/**
* Gets the basename of a plugin.
*
* This method extract the name of a plugin from its filename.
* @param string $file The filename of plugin.
* @return string The name of a plugin.
*/
function plugin_basename($file) {
$file = str_replace('\\','/',$file); // sanitize for Win32 installs
$file = preg_replace('|/+|','/', $file); // remove any duplicate slash
$file = preg_replace('|^.*/wp-content/plugins/|','',$file); // get relative path from plugins dir
return $file;
}
/**
* Hook a function on a plugin activation action hook.
*
* When a plugin is activated, the action 'activate_PLUGINNAME' hook is
* activated. In the name of this hook, PLUGINNAME is replaced with the name of
* the plugin, including the optional subdirectory. For example, when the plugin
* is located in <tt>wp-content/plugin/sampleplugin/sample.php</tt>, then the
* name of this hook will become 'activate_sampleplugin/sample.php'.
* When the plugin consists of only one file and is (as by default) located at
* <tt>wp-content/plugin/sample.php</tt> the name of this hook will be
* 'activate_sample.php'.
* @param string $file The filename of the plugin including the path.
* @param string $function the function hooked to the 'activate_PLUGIN' action.
*/
function register_activation_hook($file, $function) {
$file = plugin_basename($file);
add_action('activate_' . $file, $function);
}
/**
* Hook a function on a plugin deactivation action hook.
*
* When a plugin is deactivated, the action 'deactivate_PLUGINNAME' hook is
* deactivated. In the name of this hook, PLUGINNAME is replaced with the name of
* the plugin, including the optional subdirectory. For example, when the plugin
* is located in <tt>wp-content/plugin/sampleplugin/sample.php</tt>, then the
* name of this hook will become 'activate_sampleplugin/sample.php'.
* When the plugin consists of only one file and is (as by default) located at
* <tt>wp-content/plugin/sample.php</tt> the name of this hook will be
* 'activate_sample.php'.
* @param string $file The filename of the plugin including the path.
* @param string $function the function hooked to the 'activate_PLUGIN' action.
*/
function register_deactivation_hook($file, $function) {
$file = plugin_basename($file);
add_action('deactivate_' . $file, $function);
}
?>