转义正则表达式字符串 [英] Escaping regex string

问题描述

我想使用来自用户的输入作为搜索某些文本的正则表达式模式.它有效，但我如何处理用户将有意义的字符放入正则表达式的情况?

I want to use input from a user as a regex pattern for a search over some text. It works, but how I can handle cases where user puts characters that have meaning in regex?

比如用户要搜索Word(s):正则引擎会把(s)作为一个组.我希望它把它当作一个字符串 "(s)".我可以在用户输入上运行 replace 并用 \( 和 ) 替换 ( 和 \) 但问题是我需要为每个可能的正则表达式符号进行替换.

For example, the user wants to search for Word (s): regex engine will take the (s) as a group. I want it to treat it like a string "(s)" . I can run replace on user input and replace the ( with \( and the ) with \) but the problem is I will need to do replace for every possible regex symbol.

你知道更好的方法吗?

推荐答案

为此使用 re.escape() 函数:

4.2.3 re 模块内容

转义(字符串)

返回所有非字母数字反斜杠的字符串；如果您想匹配可能包含正则表达式元字符的任意文字字符串，这将非常有用.

Return string with all non-alphanumerics backslashed; this is useful if you want to match an arbitrary literal string that may have regular expression metacharacters in it.

一个简单的例子，搜索提供的字符串的任何出现，可选地后跟s"，并返回匹配对象.

A simplistic example, search any occurence of the provided string optionally followed by 's', and return the match object.

def simplistic_plural(word, text):
    word_or_plural = re.escape(word) + 's?'
    return re.match(word_or_plural, text)

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