常用正则

$str = ‘<div id="test">‘.
            ‘<div>1‘.                
                ‘<div>1-1‘.                    
                    ‘<div>1-1-1‘.                        
                    ‘</div>‘.
                ‘</div>‘.
            ‘</div>‘.
            ‘<div>2</div>‘.
            ‘<span>3</span>‘.
            ‘<div>4</div>‘.
        ‘</div>‘;
            
$regex = "/<div.*?id=\"test\".*?>(<.*?>.*?<\/.*?>){0,10}<\/div>/is";
preg_match ( $regex, $str, $m );  
print_r($m);