RegEx删除嵌套在bbcode标记内的bbcode标记

Question

我需要准备一个正则表达式，当它嵌套在一个预先存在的[QUOTE]标签中时，可用于删除bbcode [QUOTE]（例如：[QUOTE = name]; [QUOTE = 123; 123]）标签。

我正在使用的当前正则表达式来自这里的答案（正则表达式的完整解释）：Remove nested quotes

~\G(?!\A)(?>(\[quote\b[^]]*](?>[^[]+|\[(?!/?quote)|(?1))*\[/quote])|(?<!\[)(?>[^[]+|\[(?!/?quote))+\K)|\[quote\b[^]]*]\K~

但是，这只删除了第二个或后来的嵌套[QUOTE]标记，但是留下了一个嵌套标记，如果它们嵌套在现有的[QUOTE]标记中，我现在想要删除所有[QUOTE]标记。

输入的示例以及它应如何从preg_replace()输出：

//input
$string = 'Here is a quote [QUOTE=person]I am also quoting [QUOTE]this is a nested quote[/QUOTE][/QUOTE]';

//preg replace
$string = preg_replace('regular_expression', '', $string);

//output
echo $string;
// Here is a quote [QUOTE=person]I am also quoting[/QUOTE]

Answer 1

您可以使用递归方法：

(\[QUOTE[^][]*\])
(
    (?:[^][]+|(?R))+
)
\[/QUOTE\]

见a demo on regex101.com。

---

In PHP this would be:

$regex = '~
        (\[QUOTE[^][]*\])
        (
            (?:[^][]+|(?R))+
        )
        (\[/QUOTE\])
        ~x';

$string = 'Here is a quote [QUOTE=person]I am also quoting [QUOTE]this is a nested quote[/QUOTE][/QUOTE]';

$string = preg_replace_callback($regex, 
    function($match) {
        return $match[1] . preg_replace('~\[/?[^][]*\]~', '', $match[2]) . $match[3];
    },
    $string);

echo $string;
?>

---

This yields

Here is a quote [QUOTE=person]I am also quoting this is a nested quote[/QUOTE]