protected function getInputSource()
    {
        if (empty($this->children)) {
            return parent::getInputSource();
        }

        $childPaths = [];
        foreach ($this->children as $child) {
          $childPaths[] = $child->getInputSource();
        }

        return implode(" ", $childPaths);
    }
protected function getInputSource()
    {
        if (empty($this->children)) {
            return parent::getInputSource();
        }

        $childPaths = [];
        foreach ($this->children as $child) {
          $childPaths[] = $child->getInputSource();
        }

        return implode(" ", $childPaths);
    }
protected function getInputSource ( ) { if ( empty ( $ this -> children ) ) { return parent :: getInputSource ( ) ; } $ childPaths = [ ] ; foreach ( $ this -> children as $ child ) { $ childPaths [ ] = $ child -> getInputSource ( ) ; } return implode ( " " , $ childPaths ) ; }
Updated version which can handle multiple source files.

@return string
Updated version which can handle multiple source files .