是否有可能使regexp与所有有效的正则表达式匹配？ [英] Is it possible to have regexp that matches all valid regular expressions?

问题描述

是否可以仅使用正则表达式来检测给定的字符串是否为有效的正则表达式？

说我有一些字符串，可能是也可能不是有效的正则表达式。我想让一个正则表达式匹配那些与有效正则表达式相对应的字符串。那可能吗？还是我使用了更高层次的语法（即上下文无关语言）来检测到这一点？

如果可能的话，匹配正则表达式的正则表达式是什么？

解决方案

否，这是不可能的。这是因为有效的正则表达式涉及分组，而分组需要平衡的括号。它们必须与无上下文语法匹配。 （该文章上的第一个示例处理了圆括号。）

Is it possible to detect if a given string is valid regular expression, using just regular expressions?

Say I have some strings, that may or may not be a valid regular expressions. I'd like to have a regular expression matches those string that correspond to valid regular expression. Is that possible? Or do I have use some higher level grammar (i.e. context free language) to detect this? Does it affect if I am using some extended version of regexps like Perl regexps?

If that is possible, what the regexp matching regexp is?

解决方案

No, it is not possible. This is because valid regular expressions involve grouping, which requires balanced parentheses.

Balanced delimiters cannot be matched by a regular expression; they must instead be matched with a context-free grammar. (The first example on that article deals with balanced parentheses.)

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