class SVN_WorkspaceIterator extends FilterIterator {
    
    protected $ext = ".svn";

    public function __construct (DirectoryIterator $iterator) {
        parent::__construct($iterator);
    }

    public function accept() {
    	return ( ($this->isDir()) && (!$this->isDot()) && file_exists($this->getPathname().'/'.$this->ext));
    }
    
}

$dir = new SVN_WorkspaceIterator(new DirectoryIterator("/var/www"));

foreach ($dir as $v) {
    echo $v->getFilename(); echo "\n";
}