//: Playground - noun: a place where people can play

import UIKit

var str = "Hello, playground"

//枚舉 
// 計算屬性
// 實類方法
// 初始化
// 類擴展 extend
// 協議方法等

//枚舉語法

enum CompassPoint {
    case north
    case south
    case east
    case west
}

// 也可以寫在一行
enum Planet {
    case mercury, venus, earth, mars, jupiter, saturn, uranus, neptune
}

// 枚舉賦值
var directionToHead = CompassPoint.west

// 當已知 變量為枚舉類型時, 可以直接用 點語法來改變變量的值
directionToHead = .east



//關聯值 枚舉
// 對枚舉項 進行擴充一個附加的信息.
enum Barcode{
    case upc(Int, Int, Int, Int)
    case qrCode(String)
}

var productBarcode = Barcode.upc(8, 85909, 23987,3)
productBarcode = .qrCode("adfadfaf")


switch productBarcode {
case Barcode.upc(let numberSystem, let manufacturer, let product, let check):
    print("UPC : \(numberSystem), \(manufacturer), \(product), \(check))")
case .qrCode(let productCode):
    print("QR code \(productCode)")
}


//把 let 和 var 提取出來 放到 case name 前面
switch productBarcode {
case let .upc(numberSystem, manufacturer, product, check):
    print("UPC : \(numberSystem), \(manufacturer), \(product), \(check))")

case let .qrCode(productCode):
    print("QR code \(productCode)")
}

//枚舉中的類型可以不一樣
enum some{
    case afadf
    case second(Int,Int)
}


//原始值 枚舉 在編譯的時候就已經有值了
// 要明確申明 枚舉的類型
enum ASIIControlCharacter:Character{
    case tab = "\t"
    case lineFeed = "\n"
    case carriageReturn = "\r"
}


// 含蓄的原始值類型 枚舉
// mercury 明確設值為 1, 系統會自動推算出后面的值.如 venus = 2. earch = 3 等
enum PlanetOne:Int{
    case mercury = 1, venus, earth, mars, jupiter, saturn, uranus, neptune
}

// 當原始值為 String 類型時, case 項都沒有設置默認值, 則 case 的默認值為自己本身 如 north = "north" south = "south" 等
enum CompassPointOne: String {
    case north, south, east, west
}


// 獲取 原始值枚舉的  原始值

let earthOrder = PlanetOne.earth.rawValue // = 3

let sunsetDiraction = CompassPointOne.west.rawValue// = "west"

// 用原始值來初始化 枚舉類型數據.
//原始值 為 5, 這里的原始值必須是我們定義 枚舉型所有原始值中的一個, 這樣才會返回一個正確的枚舉類型. 如果是非法的原始值 則返回 nil , 所有用原始值來初始化枚舉類型 結果是一個可選值
let possiblePlanet = PlanetOne(rawValue: 5)

// 這里用原始值 "north" 來初始化
let possibleCompass = CompassPointOne(rawValue: "north")


//用原始值初始化枚舉類型 綜合使用

let positionTofind = 11 // 判斷太陽系 第11顆行星是什么? 實際上 沒有11 這個行星
if let somePlanet = PlanetOne(rawValue: positionTofind){
    switch somePlanet {
    case .earth:
        print("Mostly harmless")
    default:
        print("Not a safe place for humans")
    }
} else{
    print("There isn't a planet at position")
}
// 打印:There isn't a planet at position




//遞歸枚舉

enum ArithmeticExpression{
    case number(Int)
    indirect case addition(ArithmeticExpression,ArithmeticExpression)
    indirect case mutiplication(ArithmeticExpression,ArithmeticExpression)
}

// 上面的枚舉也可以寫作
indirect enum ArithmeticExpressionOne{
    case number(Int)
    case addition(ArithmeticExpression,ArithmeticExpression)
    case mutiplication(ArithmeticExpression,ArithmeticExpression)
}

//如: 我們要實現表達式 (5+4)*2
let five = ArithmeticExpression.number(5)
let four = ArithmeticExpression.number(4)
let sum = ArithmeticExpression.addition(five, four)
let product = ArithmeticExpression.mutiplication(sum, ArithmeticExpression.number(2))

func evalute(_ expression:ArithmeticExpression) ->Int{
    switch expression {
    case let .number(value):
        return value
    case let .addition(left, right):
        return evalute(left) + evalute(right)
    case let .mutiplication(left,right):
        return evalute(left) * evalute(right)
    }
}

print(evalute(product))

//上面這個例子很有意思


//枚舉中 含有方法

enum State {
        case ready, executing, finished
        func keyPath() -> String {
            switch self {
            case .ready:
                return "isReady"
            case .executing:
                return "isExecuting"
            case .finished:
                return "isFinished"
            }
        }
    }
let currentState = State.ready
 

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