php正则组平衡问题
Compilation failed: syntax error in subpattern name (missing terminator) at offset 46

PHP code

$str = "<div class='a'><div>cc</div>a<span>ab</span>c<div class='b'>xxxy</div></div>";
preg_match_all("#((?'open'<div[^>]*>)((?:.(?!</?div))*.)*?)((?'-open'</div[^>]*>)((?:.(?!</?div))*.)*?)#is",$str,$matches); 
print_r($matches);

 

请教一下，是不是PHP 不支持组平衡啊

------解决方案--------------------
"#((?'open'<div[^>]*>)((?:.(?!</?div))*.)*?)((?:'-open'</div[^>]*>)((?:.(?!</?div))*.)*?)#is",