不是一步到位.正则表达式不能是自引用的.它们首先被构建，然后被使用.一旦构建了正则表达式，就无法重新构建/扩充.

Not in one step. Regular expressions cannot be self-referential. They are first built, and then used. No re-building/augmenting is possible once the regex is built.

您可以像之前一样匹配长度信息，并在第二步中使用它，同时评估匹配.

You can match the length info as you already do and use it in a second step, while evaluating the matches.

先发制人的评论:我知道可以用 "(.)\1" 来匹配同一个字符两次.不过，这不是我所说的自我参照".

Preemptive comment: I know that one can do "(.)\1" to match the same character twice. This is not what I mean with "self-referential", though.