Kas on võimalik oma andmestruktuuris Copy-on-write toe rakendada?

Yes, support for Copy-on-write (COW) can be implemented in your own data structure. The idea of COW is that multiple objects can share the same data until it needs to be modified. When a modification is attempted, a copy of the data is made so that changes do not affect other objects.

In iOS and Swift, this is often implemented using reference counting and checking if the object is unique before modifying it. It can be approximately done like this:

class CowBuffer {
    private var data: [Int]
    private var isUniquelyReferenced: Bool {
        return isKnownUniquelyReferenced(&data)
    }

    init(data: [Int]) {
        self.data = data
    }

    func modify(at index: Int, value: Int) {
        if !isUniquelyReferenced {
            data = data.map { $0 } // create a copy
        }
        data[index] = value
    }
}

This way, the data copy is only created when necessary, saving memory and improving performance.