PAT 好讀版

PAT.swift

// 有 associatedtype 的 protocol
public protocol IteratorProtocol {
  associatedtype Element
  mutating func next() -> Element?
}

// 有 Self 的 protocol, Hashable 的 Self 來自所繼承的 Equatable
public protocol Hashable: Equatable {
  var hashValue: Int { get }
  func hash(into hasher: inout Hasher)
  func _rawHashValue(seed: Int) -> Int
}

public protocol Equatable {
  static func == (lhs: Self, rhs: Self) -> Bool
}

// 以下寫法都會被 compiler 抱怨
// Protocol XXX can only be used as a generic constraint because it has Self or associated type requirements
func generateDictionaryKey() -> Hashable {
  return 8
}

func getIterator() -> IteratorProtocol {
    return ["1", "2", "3"].makeIterator()
}