Java Regex引擎崩溃 [英] Java Regex Engine Crashing

问题描述

正则表达式 - （[^ =]（\\\\ * [\\w - 。] *）* $）

测试字符串 - paginationInput.entriesPerPage = 5

Java Regex引擎崩溃/采取年龄（> 2分钟）寻找比赛。以下测试输入不是这种情况：

Java Regex Engine Crashing / Taking Ages (> 2mins) finding a match. This is not the case for the following test inputs:

paginationInput=5

paginationInput.entries=5

我的要求是获取右侧的字符串 of = 并将其替换为某些内容。除了上面提到的输入外，上面的模式做得很好。

My requirement is to get hold of the String on the right-hand side of = and replace it with something. The above pattern is doing it fine except for the input mentioned above.

我想了解错误的原因以及如何根据我的要求优化Regex以避免其他特殊情况。

I want to understand why the error and how can I optimize the Regex for my requirement so as to avoid other peculiar cases.

推荐答案

您可以使用后面的外观来确保您的字符串从<$ c $之后的字符处开始c> = ：

You can use a look behind to make sure your string starts at the character after the =:

(?<=\\=)([\\s\\w\\-.]*)$

至于为什么它崩溃了，这是该组周围的第二个 * 。我不确定你为什么需要它，因为这听起来像你要求：

As for why it is crashing, it's the second * around the group. I'm not sure why you need that, since that sounds like you are asking for :

• 单个字符，除了等于


• 然后0或更多重复以下组：
  
  
  
  • 任何数量的空格
  
  
  • 然后任意数量的单词字符，短划线或点
  
  

  无论如何，取出 * ，它不再永远旋转，但我仍然会使用更具体的正则表达式看看背后的情况。

  Anyway, take out that *, and it doesn't spin forever anymore, but I'd still go for the more specific regex using the look behind.

  另外，我不知道你是怎么用的，但为什么你有 $ 在那里？然后你只能匹配字符串中的最后一个（如果你有多个）。看起来你会更好地预测新行或结束：（？= \\ n | $）

  Also, I don't know how you are using this, but why did you have the $ in there? Then you can only match the last one in the string (if you have more than one). It seems like you'd be better off with a look-ahead to the new line or the end: (?=\\n|$)

  [修改]：更新以下评论。

  [Edit]: Update per comment below.

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