<?php
	function f2f($string){
		$list = get_defined_functions();
		foreach($list["internal"] as $f)
			if(preg_match('#(=|\s|\()+\b'.$f.'\b\s*\(#i', $string))
				$ret[] = $f;
			
		return $ret;
	}
	
	print_r(f2f(file_get_contents("test.php")));
?>