Attaches the specified PHP function to the specified filter hook. Thus, when the filter is triggered, the value will be filtered by the specified PHP function.
Call the functions added to a filter hook.
Retrieve the name of the current filter or action.
Retrieve the name of a filter currently being processed.
Check if any filter has been registered for a hook.
Remove all of the hooks from a filter.
Removes a function from a specified filter hook.