寻找正则表达式来转义特殊字符集

Question

The goal is to replace characters in string such as _ and * that have special role in Markdown with \\_ and \\* respectively.

My current method looks like this:

text = "Text *here* should be _formatted_"
specials = ["*", "_"]
for char in specials:
    text = text.replace(char, f"\\{char}")

Wondering if there is alternative way of achieving this functionality with regular expressions.

Answer 1

Its possible to use this in a re.sub() function to escape special characters
that aren't already escaped.

r"(?<?\\)((::\\\\)*)([*_])"

https://regex101.com/r/8LNp5E/1

Example Python

>>> import re
>>> target = (
...    r"The goal is to replace characters in string such as _ and * in that have" + "\n"
...    r"special role in Markdown \\_ and \\*  and  \_ and \* ." + "\n"
...   )
>>>
>>> res = re.sub( r"(?<!\\)((?:\\\\)*)([*_])", r"\1\\\2", target )
>>>
>>> print ( res )
The goal is to replace characters in string such as \_ and \* in that have
special role in Markdown \\\_ and \\\*  and  \_ and \* .