[Skunkworks] PHP Question

Good people, I have a small question: suppose I have a string with native PHP or user defined functions names separated with a known separator, e.g. $myString = "strip_tags|trim|myFunction"; And I want to apply each function name to some other data e.g. $cleanData = strip_tags(trim(myFunction($dirtyData))); How would I go about it? It has been done in CodeIgniter form validation library but for the life of me I can't see how to reverse engineer it.