RotorBox.cipher.swift

public struct RotorBox {
        
        ...

        public mutating func cipher(_ target: Token) -> Token {
                defer {
                    // 関数を抜ける際に回転
                    rotate()
                }

                // 入力→rotor0
                let input = connect(pure, rotor0)(target)
                let r0 = rotor0.forward(input)
                // rotor0→rotor1
                let _r0 = connect(rotor0, rotor1)(r0)
                let r1 = rotor1.forward(_r0)
                // rotor1→rotor2
                let _r1 = connect(rotor1, rotor2)(r1)
                let r2 = rotor2.forward(_r1)
                // rotor2→reflector
                let _r2 = connect(rotor2, reflector)(r2)
                let ref = reflector.forward(_r2)
                // reflector→rotor2
                let _ref = connect(reflector, rotor2)(ref)
                let r2ret = rotor2.backward(_ref)
                // rotor2→rotor1
                let _r2ret = connect(rotor2, rotor1)(r2ret)
                let r1ret = rotor1.backward(_r2ret)
                // rotor1→rotor0
                let _r1ret = connect(rotor1, rotor0)(r1ret)
                let r0ret = rotor0.backward(_r1ret)
                // rotor0→出力
                let output = connect(rotor0, pure)(r0ret)

                return output
        }

        private mutating func rotate() {
                mod1 = (mod1 + 1) % 26
                mod2 = (mod2 + 1) % (26 * 26)
                rotor0.rotate()
                if mod1 == 0 {
                    rotor1.rotate()
                }
                if mod2 == 0 {
                    rotor2.rotate()
                }
        }

        private func connect(_ input: Rotor, _ output: Rotor) -> (Token) -> Token {
                let gap = input.position - output.position
                return { token in
                    return token - gap
                }
        }
}