// MARK: - Regular Expression
private extension String
{
    func regexp(_ pattern: String) -> NSRegularExpression {
        do {
            let regexp: NSRegularExpression = try NSRegularExpression(pattern: pattern, options: [NSRegularExpression.Options.caseInsensitive])
            return regexp
        } catch {
            fatalError("regular expression pattern is invalid.")
        }
    }
}

// MARK: - Regular Expression
public extension String
{
    public func regexMatched(withPattern pattern: String) -> Bool {
        let regexp: NSRegularExpression = self.regexp(pattern)
        return 0 < regexp.numberOfMatches(in: self, options: [], range: NSRange(location: 0, length: (self as NSString).length))
    }

    public func regexStrings(withPattern pattern: String) -> [String] {
        let regexp: NSRegularExpression = self.regexp(pattern)
        let matches: [NSTextCheckingResult] = regexp.matches(in: self, options: [], range: NSRange(location: 0, length: (self as NSString).length))
        let result: [String] = matches.map { (match: NSTextCheckingResult) in
            (self as NSString).substring(with: match.range)
        }
        return result
    }

    public func regexReplace(withPattern pattern: String, replace: String) -> String
    {
        let regexp: NSRegularExpression = self.regexp(pattern)
        let matches: [NSTextCheckingResult] = regexp.matches(in: self, options: [], range: NSRange(location: 0, length: (self as NSString).length))
        var result: String = self
        matches.reversed().forEach { (match: NSTextCheckingResult) in
            result = (result as NSString).replacingCharacters(in: match.range, with: replace)
        }
        return result
    }
}