c# - 将 C# 函数转换为 Swift 4.2

Question

我找到了 this thread谈论this article .我在线程中发现了一些代码，看起来 正是我的项目所需要的。但是，它是用 C# 编写的，我不知道如何将它翻译成 Swift。

C#代码:

[Flags]
public enum Directions
{
    NorthWest  = 1 << 0,
    North = 1 << 1,
    NorthEast   = 1 << 2,
    West   = 1 << 3,
    East  = 1 << 4,
    SouthWest = 1 << 5,
    South   = 1 << 6,
    SouthEast   = 1 << 7,
}

private static Directions CalculateTileFlags(bool east, bool west, bool north, bool south, bool northWest, bool northEast, bool southWest, bool southEast)
{
    var directions = (east ? Directions.East : 0) | (west ? Directions.West : 0)  | (north ? Directions.North : 0) | (south ? Directions.South : 0);
    directions |= ((north && west) && northWest) ? Directions.NorthWest : 0;
    directions |= ((north && east) && northEast) ? Directions.NorthEast : 0;
    directions |= ((south && west) && southWest) ? Directions.SouthWest : 0;
    directions |= ((south && east) && southEast) ? Directions.SouthEast : 0;
    return directions;
}

到目前为止我的尝试:

var Flags = [Int]()
enum Directions : Int {
    case NorthWest
    case North
    case NorthEast
    case West
    case East
    case SouthWest
    case South
    case SouthEast

    func getTuple() -> Int {
        switch self {
        case .NorthWest:
            return 1 << 0
        case .North:
            return 1 << 1
        case .NorthEast:
            return 1 << 2
        case .West:
            return 1 << 3
        case .East:
            return 1 << 4
        case .SouthWest:
            return 1 << 5
        case .South:
            return 1 << 6
        case .SouthEast:
            return 1 << 7
        }
    }
}

我得到了那个部分。很容易。该功能是我不太清楚的部分。我想我很接近，但我不知道。

func CalculateTileFlags(east: Bool, west: Bool, north: Bool, south: Bool,
                            northWest: Bool, northEast: Bool, southWest: Bool, southEast: Bool) -> Int {

    var eastD = Directions.East.getTuple()
    var westD = Directions.West.getTuple()
    var northD = Directions.North.getTuple()
    var southD = Directions.South.getTuple()
    var northWestD = Directions.NorthWest.getTuple()
    var northEastD = Directions.NorthEast.getTuple()
    var southWestD = Directions.SouthWest.getTuple()
    var southEastD = Directions.SouthEast.getTuple()

    var directions = east ? true : false || west ? true : false || north ? true : false || south ? true : false

    directions != ((north && west) && northWest) ? northWestD : 0
    directions != ((north && east) && northEast) ? northEastD : 0
    directions != ((south && west) && southWest) ? southWestD : 0
    directions != ((south && east) && southEast) ? southEastD : 0

    return directions
}

我需要帮助才能正确翻译此函数，以便它返回 255 以下的 47 个可能的整数。

Answer 1

在 Swift 中，OptionSet 是最接近枚举的数据结构，在其他语言中具有移位值:

您的 C# 代码可以翻译如下:

struct Directions: OptionSet {
    var rawValue: Int
    init(rawValue: Int) {self.rawValue = rawValue}

    static let northWest = Directions(rawValue: 1 << 0)
    static let north     = Directions(rawValue: 1 << 1)
    static let northEast = Directions(rawValue: 1 << 2)
    static let west      = Directions(rawValue: 1 << 3)
    static let east      = Directions(rawValue: 1 << 4)
    static let southWest = Directions(rawValue: 1 << 5)
    static let south     = Directions(rawValue: 1 << 6)
    static let southEast = Directions(rawValue: 1 << 7)
}

extension Directions {
    static func calculateTileFlags(
        east: Bool = false,
        west: Bool = false,
        north: Bool = false,
        south: Bool = false,
        northWest: Bool = false,
        northEast: Bool = false,
        southWest: Bool = false,
        southEast: Bool = false) -> Directions
    {
        var directions: Directions = [
            east ? Directions.east : [],
            west ? Directions.west : [],
            north ? Directions.north : [],
            south ? Directions.south : [],
        ]

        directions.formUnion((north && west) && northWest ? Directions.northWest : [])
        directions.formUnion((north && east) && northEast ? Directions.northEast : [])
        directions.formUnion((south && west) && southWest ? Directions.southWest : [])
        directions.formUnion((south && east) && southEast ? Directions.southEast : [])

        return directions
    }
}