在Golang中使用正则表达式确保特定的字符在字符串中，而不管位置如何

Question

I am building a super simple function to ensure a password contains specific characters. Namely, the password should have the following:

• One lowercase letter
• One uppercase letter
• One digit
• One special character
• No white space, #, or |

I thought regex would be the simplest way to go about doing this. But, I am having a hard time figuring out how to do this in Golang. Currently, I have a bunch of separate regex MatchString functions which I will combine to get the desired functionality. For example:

lowercaseMatch := regexp.MustCompile(`[a-z]`).MatchString
uppercaseMatch := regexp.MustCompile(`[A-Z]`).MatchString
digitMatch := regexp.MustCompile(`\d`).MatchString
specialMatch := regexp.MustCompile(`\W`).MatchString
badCharsMatch := regexp.MustCompile(`[\s#|]`).MatchString
if (lowercaseMatch(pwd) 
        && uppercaseMatch(pwd) 
        && digitMatch(pwd)
        && specialMatch(pwd)
        && !badCharsMatch(pwd)) {
    /* password OK */
} else {
    /* password BAD */
}

While this makes things pretty readable, I would prefer a more concise regex, but I don't know how to get regex to search for a single character of each of the above categories (regardless of position). Can someone point me in the right direction of how to achieve this? Additionally, if there is a better way to do this than regex, I am all ears.

Thanks!

Answer 1

Since golang use re2, it doesn't support positive-lookahead (?=regex), so I'm not sure if there is a way to write a regex that cover all cases.

Instead, you can use unicode package:

func verifyPassword(s string) bool {
    var hasNumber, hasUpperCase, hasLowercase, hasSpecial bool
    for _, c := range s {
        switch {
        case unicode.IsNumber(c):
            hasNumber = true
        case unicode.IsUpper(c):
            hasUpperCase = true
        case unicode.IsLower(c):
            hasLowercase = true
        case c == '#' || c == '|':
            return false
        case unicode.IsPunct(c) || unicode.IsSymbol(c):
            hasSpecial = true
        }
    }
    return hasNumber && hasUpperCase && hasLowercase && hasSpecial
}