[\ s \ S] *之间有什么区别？和。*？

I've encountered the following token in a regular expression: [\s\S]*?

我在正则表达式中遇到了以下标记：[\ s \ S] *？

If I understand this correctly, the character class means "match a whitespace character or a non-whitespace character". Therefore, would this not do exactly the same thing as .*?

如果我理解正确，字符类意味着“匹配空白字符或非空白字符”。因此，这不会与。*完全相同吗？

One possible difference is that usually . does not match newlines. However, this regular expression was written in Ruby and was passed the m modifier meaning that the . does, in fact, match newlines.

一个可能的区别是通常。与换行符不匹配。但是，这个正则表达式是用Ruby编写的，并且传递了m修饰符，意思是。事实上，确实匹配换行符。

Is there any other reason to use [\s\S]*? instead of .*?

有没有其他理由使用[\ s \ S] *？代替。*？

In case it helps, the regular expression I am looking at appears inside the sprockets library in the HEADER_PATTERN constant on line 97. The full expression is:

如果它有帮助，我正在查看的正则表达式出现在第97行的HEADER_PATTERN常量的sprockets库中。完整的表达式是：

/
  \A \s* (
    (\/\* ([\s\S]*?) \*\/) |
    (\#\#\# ([\s\S]*?) \#\#\#) |
    (\/\/ ([^\n]*) \n?)+ |
    (\# ([^\n]*) \n?)+
  )
/mx

3 个解决方案

#1

You interpreted the regex correctly.

您正确解释了正则表达式。

That seems like a relict from other languages which do not support the m-flag (or s-flag in other implementations).

这似乎是来自其他语言的遗留物，它们不支持m-flag（或其他实现中的s-flag）。

A reason to use that construct would be to not use the m-flag so you have the possibility to use . without matching newlines but are still able to match everything if need be.

使用该结构的一个原因是不使用m-flag，因此您可以使用。没有匹配换行符，但如果需要，仍然可以匹配所有内容。

#2

With the m flag, they would be the same except that .* would be a lot clearer and easier to maintain.

使用m标志，它们将是相同的，除了。*将更清晰，更容易维护。

#3

The newline thing is the only difference. Maybe somebody thought it was easier to read without having to know the m context, or wanted it to be robust against a change to that context.

换行符是唯一的区别。也许有人认为在不必了解m上下文的情况下阅读更容易，或者希望它能够在更改上下文时保持健壮。

I have seen [^]* used for a similar purpose.

我见过[^] *用于类似目的。

#1