如何取消转义的正则表达式？

Question

I'm looking for the reverse of regexp.QuoteMeta. Is it there a such function?

I've tried to manually unescape it using strings.Replace("\", "", -1) but this is prone to error/unreliable as it doesn't work in all the cases(i.e. on excessive escaping or unicode).

I also tried to add some quotes and use strconv.Unquote (e.g. strconv.Unquote("+ "https:\/\/ad.doubleclick.net" +") ) but it errors out.

Answer 1

Parse the string with the regexp/syntax package to get the unquoted string:

func unquoteMeta(s string) (string, error) {
    r, err := syntax.Parse(s), 0)
    if err != nil {
        return "", err
    }
    if r.Op != syntax.OpLiteral {
        return "", errors.New("not a quoted meta")
    }
    return string(r.Rune), nil
}

playground example