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Xcode抱怨说:“无法指定类型节点的值来键入节点< _>?”在第23,24,26,27行(在排队的条件部分中'节点'到'顶部'和'底部'的分配)。我不知道这意味着什么,以及为什么Xcode中看到了该类型的节点和顶/差异底部无法将节点类型为<T>的值分配给类型节点<_>?
class Node<T> {
var key: T?
weak var next: Node<T>?
weak var previous: Node<T>?
init(key: T, previous: Node? = nil) {
self.key = key
self.previous = previous
}
}
class Dequeue<T> {
private var count: Int = 0
private weak var top: Node<T>?
private weak var bottom: Node<T>?
func enqueue<T>(val: T) {
// if dequeue is empty
let node = Node<T>(key: val)
if top == nil {
self.top = node
self.bottom = node
} else {
self.bottom?.next = node
self.bottom = node
}
}
}