SwitchExpression.swift

SwitchExpression.swift

@_functionBuilder struct SwitchExpression {
    static func buildBlock<T>(_ content: T) -> T {
        return content
    }

    static func buildEither<T>(first: T) -> T {
        return first
    }

    static func buildEither<T>(second: T) -> T {
        return second
    }
}

func switchExpression(@SwitchExpression _ content: () -> String) -> String {
    return content()
}

enum MyEnum {
    case one
    case two
    case three
}

// 1
let enumValue1 = MyEnum.one
let computedValue1: String
switch enumValue1 {
case .one: computedValue1 = "one"
case .two: computedValue1 = "two"
case .three: computedValue1 = "three"
}

// 2
let enumValue2 = MyEnum.two
let computedValue2 = switchExpression {
    switch enumValue2 {
    case .one: "Hey"
    case .two: "What up"
    case .three: "Yo"
    }
}