code: public function compileSource($source) {
          $source = $this->stripComments($source);
          $source = $this->saveLiterals($source);
  
          $result = preg_replace_callback('#' . $this->_config['tokenStart'] . '(.*)' . $this->_config['tokenEnd'] . '#smU', array($this, 'onTokenFound'), $source);
          $result = $this->restoreLiterals($result);
          return $result;
      }
docs: Main compilartor function
  @param $source
  @return mixed