What is a convenient way to work with OptionSet?

Question

I work on a project with many bitwise option sets and each of them contains many options with all option e.g:

struct MyOption: OptionSet {
    let rawValue: Int
    
    static let a = Self(rawValue: 1 << 0)
    static let b = Self(rawValue: 1 << 1)
    static let c = Self(rawValue: 1 << 2)
    ...
    static let last = Self(rawValue: 1 << N)
    
    static let all: Self = [.a, .b, .c, ..., .last]
}

It requires to maintain much of similar code so is it any way to eliminate hardcoded bitwise shift operations and the all option?

Answer 1

You can use next OptionSet's extension which implements all option and a convenient initializer:

extension OptionSet where RawValue == Int {
    static var all: Self {
        Self.init(rawValue: Int.max)
    }
    
    init(_ shift: Int) {
        self.init(rawValue: 1 << shift)
    }
}

Then you can re-write your option set:

struct Option: OptionSet {
    let rawValue: Int
    
    static let a = Self(0)
    static let b = Self(1)
    static let c = Self(2)
}

Option.a.rawValue // 1
Option.b.rawValue // 2
Option.c.rawValue // 4

let options: Option = [.a, .b]
Option.all.contains(options) // true