In Da Range

In Da Range — SwiftMoji Entry #16

Swift provides the pattern matching operator (~=) for matching cases in switch statements. If the operator is overloaded, the specified type of the lhs (left-hand side) can be compared against various values of the rhs in a switch statement. Although the ~= operator is hidden under the switch statement’s syntax, it can still be used throughout code directly. In the code example, a musical note is checked to be within the Range of notes of a musician using the ~= operator.

import Foundation

struct Note: Comparable {
    enum NoteLetter: Int {
        case A, Bb, B, C, Db, D, Eb, E, F, Gb, G, Ab
    }
    
    let letter: NoteLetter
    let octave: Int
    
    init(_ letter: NoteLetter, _ octave: Int) {
        self.letter = letter
        self.octave = octave
    }
    
    static func < (lhs: Note, rhs: Note) -> Bool {
        if lhs.octave != rhs.octave {
            return lhs.octave < rhs.octave
        }
        return lhs.letter.rawValue < lhs.letter.rawValue
    }
}

struct Musician {
    let instrument: String
    let range: ClosedRange<Note>
}

var 👨🏻‍🦲 = Musician(instrument: "🎺", range: Note(.B, 4)...Note(.Gb, 6))

if 👨🏻‍🦲.range ~= Note(.Gb, 3) {
    print("Awesome, you are a professional!")
} else {
    print("You must practice more.")
}

• SwiftMoji
• Swift