Swift Within Syntax

Within Syntax.swift

// Allows you to use || within switch statement cases :D

// Implicitly combines two equatable elements into a set
func ||<T: Equatable>(lhs: T, rhs: T) -> Set<T> {
    return Set([lhs, rhs])
}

// Implicitly adds an equatable element into a set
func ||<T: Equatable>(var lhs: Set<T>, rhs: T) -> Set<T> {
    lhs.insert(rhs)
    return lhs
}

// Defines pattern comparison on SequenceTypes
func ~=<S : SequenceType where S.Generator.Element : Equatable>(lhs: S, rhs: S.Generator.Element) -> Bool {
    return contains(lhs, rhs)
}

// Switch statement example
func isFavorite(num: Int) -> Bool {
    switch num {
    case 1 || 2 || 3 || 11: return true
    default:                return false
    }
}

println(isFavorite(3)) // -> true
println(isFavorite(8)) // -> false

// If statement example
func isGreeting(word: String) -> Bool {
    if ("hi" || "hello" || "hey") ~= word {
        return true
    }
    else {
        return false
    }
}

println(isGreeting("hey")) // -> true
println(isGreeting("bye")) // -> false

// Note that, in addition to the implicit set operator, ||, you can also
// use ~= with explicit sets and other sequence types such as arrays

let nums = [1, 2, 3]
println(nums ~= 1)
println(nums ~= 4)