Swift 5中的树数据结构

Question

我是新手，我实现了这样的树数据结构。它工作正常。我唯一想知道的是，此解决方案中是否存在任何内存泄漏。

如果是，我该如何治愈？如果没有，我是否应该记住一个特定条件以避免或检测内存泄漏？

import Foundation

struct Queue<Element> {

    var elements : [Element] = []
    var isEmpty : Bool {
        return elements.isEmpty
    }

    @discardableResult
    mutating func Enqueue (_ element : Element) -> Bool{
        elements.append(element)
        return true
    }

    mutating func Dequeue() -> Element? {
        return isEmpty ? nil : elements.removeFirst()
    }

}

class TreeNode<T> {

    var value : T
    var children : [TreeNode] = []

    init(_ value : T) {

    self.value = value

    }

    func addChild(_ child : TreeNode) {
        self.children.append(child)
    }

}

extension TreeNode where T : Equatable{

    //for depth first traversal
    func forEachDepthFirst(_ visit : (TreeNode) -> Void) {

        visit(self)

        children.forEach {

            $0.forEachDepthFirst(visit)

        }

    }

    //for level order traversal
    func forEachLevelOrder(_ visit : (TreeNode) -> Void) {

        visit(self)
        var queue = Queue<TreeNode>()
        children.forEach {
            queue.Enqueue($0)
        }
        while let node = queue.Dequeue() {
            visit(node)
            node.children.forEach { queue.Enqueue($0)}
        }

    }

    //searching in a tree
    func search(_ value : T) -> TreeNode? {
        var result : TreeNode?
        forEachLevelOrder { node in
            if node.value == value {
                result = node
            }
        }

        return result
    }

}

//操作

let coffee = TreeNode<String>("Coffee")

let hot = TreeNode<String>("Hot")
let cold = TreeNode<String>("Cold")

coffee.addChild(hot)
coffee.addChild(cold)

let cappucino = TreeNode<String>("Cappucino")
let regular = TreeNode<String>("Regular")
let americano = TreeNode<String>("Americano")

hot.addChild(cappucino)
hot.addChild(regular)
hot.addChild(americano)

let coldCoffee = TreeNode<String>("Cold Coffee")
let specialCold = TreeNode<String>("Special Cold")

cold.addChild(coldCoffee)
coldCoffee.addChild(specialCold)

//coffee.forEachDepthFirst {
//    print($0.value)
//}

//coffee.forEachLevelOrder {
//    print($0.value)
//}

if let searchResult = coffee.search("Special Cold") {
    print(searchResult.value)
}

谢谢。