在正则表达式中重用字符类 [英] Reusing a character class in a regular expression

问题描述

为了使正则表达式更简短，是否有一种简便的方法来引用同一正则表达式中较早出现的字符类?

In order to keep a regular expression more brief, is there a shorthand way to refer to a character class that occurs earlier in the same regular expression?

示例

有没有一种方法可以缩短以下时间:

Is there a way to shorten the following:

[acegikmoqstz@#&].*[acegikmoqstz@#&].*[acegikmoqstz@#&]

推荐答案

请记住，正则表达式功能取决于所使用的语言.

Keep in mind that regex features are dependant on the language being used.

使用Java，您可以执行以下操作:

With Java, you can do this:

[acegikmoqstz@#&](?:.*[acegikmoqstz@#&]){2}

仅此而已，使用Java不能引用命名子模式.

But that's all, with java you can't refer to named subpattern.

使用PHP可以做到:

(?(DEFINE)(?<a>[acegikmoqstz@#&]))\g<a>(?:.*\g<a>){2}

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