nested-containers.swift

import Foundation

class MutableBox<T> {
    var value: T
    
    init(_ initialValue: T) {
        value = initialValue
    }
}

class Unboxed {
    var d: [Int: [Int: Set<Int>]] = [:]
    
    func run() {
        d[0] = [:]
        d[0]?[0] = []
        
        let pi = ProcessInfo.processInfo
        
        var last = pi.systemUptime
        
        for i in 0... {
            let now = pi.systemUptime
            print(i, now - last)
            last = now
            d[0]?[0]?.insert(i)
        }
    }
}

class Boxed {
    var d: [Int: [Int: MutableBox<Set<Int>>]] = [:]
    
    func run() {
        d[0] = [:]
        d[0]?[0] = MutableBox([])
        
        let pi = ProcessInfo.processInfo
        
        var last = pi.systemUptime
        
        for i in 0... {
            let now = pi.systemUptime
            print(i, now - last)
            last = now
            d[0]?[0]?.value.insert(i)
        }
    }
}

//Unboxed().run()
Boxed().run()