Hashing McGlashing

Hashing McGlashing — SwiftMoji Entry #11

Conformance to the Hashable protocol allows each 👤 in a set to be uniquely identified as long as one property is distinct. This unique ID called a hash value can be used to search a Set for a member in constant time (O(1)). This efficiency is a result of the contains(_:) method having direct access to each corresponding memory address in a hash table, instead of being required to iterate over each Element as in Arrays. As of Swift 4.2, the implementation of the underlying hashValue computed property is automatically provided by passing a value’s properties into the Hasher struct’s combine(_:) method and then using the finalize() method to obtain the Int.

struct 👤: Hashable {
    let name: String
    let age: Int
    let apartmentNumber: Int
    let ownsPets: Bool
}

typealias 📩 = String

struct 📪 {
    var contents = [📩]()
}

struct 🏢 {
    let residents: Set<👤>
    var mailbox = 📪()
}

var 🏠 = 🏢(residents: [
    👤(name: "Nicolas", age: 21, apartmentNumber: 315, ownsPets: false),
    👤(name: "Sam McGlashing", age: 50, apartmentNumber: 118, ownsPets: true),
    👤(name: "Jonah", age: 35, apartmentNumber: 220, ownsPets: true),
    👤(name: "Sam McGlashing", age: 25, apartmentNumber: 305, ownsPets: true)
])

let 👨🏼‍🦳 = 👤(name: "Sam McGlashing", age: 50, apartmentNumber: 118, ownsPets: true)
let 💌 = "Hello Sam!"

if 🏠.residents.contains(👨🏼‍🦳) {
    🏠.mailbox.contents.append(💌)
}

• SwiftMoji
• Swift