stack.transcoder.swift

extension Stack {
    struct Transcoder: Codable {
        enum CodingKeys: String, CodingKey { case elements }
        let stack: Stack<T>
        init(stack s:Stack<T>) { stack = s }
        init(from decoder: Decoder) throws {
            stack = Stack(createStack(with:try decoder.container(keyedBy:CodingKeys.self).decode(Array<T>.self,forKey:.elements)))
        }
        func encode(to encoder: Encoder) throws {
            var container = encoder.container(keyedBy: CodingKeys.self)
            var elements: [T] = []
            while let x = stack.pop() { elements.append(x) }
            try container.encode(elements, forKey: .elements)
        }
    }
}