Int Extraction Sampler

String+Int.swift

//So MyString[3] just works. Don't use in projects with real input. 
extension StringProtocol {
    subscript(offset: Int) -> Character {
        self[index(startIndex, offsetBy: offset)]
    }
}

extension StringProtocol {

    //Ignores negative signs. 
    func extractPositiveInts() -> [Int] {
        self.components(separatedBy: CharacterSet.decimalDigits.inverted).compactMap({Int($0)})
    }

    //Will find the neagive signs. Will not validate that they are negative signs in context.
    func extractInts() -> [Int] {
        self.components(separatedBy: CharacterSet.decimalDigits.inverted.union(CharacterSet(charactersIn:"-"))).compactMap({Int($0)})
    }
  
     //Doesn't require Foundation, but does require a contains check. 
    func extractInts_splitWhere() -> [Int] {
        self.split(whereSeparator: {!"-0123456789".contains($0)}).compactMap({Int($0)})
    }

    //For when there is only one separator mixed in (only knocks out the seperator, so not really an extractInt)
    func extractInts(separator:Self.Element) -> [Int] {
        self.split(separator:separator).compactMap { Int($0)}
    }
    
    //Takes all the decimalDigits and slurps them into one number. 
    func schlurpPositiveInt() -> Int {
        let filteredString = self.unicodeScalars.filter {
            CharacterSet.decimalDigits.contains($0)
        }.compactMap { Character($0)  }
        return Int(String(filteredString))!
    }
}