swift - 选项集更惯用的快速测试？

Question

仍然习惯在 Swift 中使用 OptionSetType。

在好的 ol' C 中，如果我有类似的东西

typedef enum {
    CHAR_PROP_BROADCAST          =0x01,
    CHAR_PROP_READ               =0x02,
    CHAR_PROP_WRITE_WITHOUT_RESP =0x04,
    CHAR_PROP_WRITE              =0x08,
    CHAR_PROP_NOTIFY             =0x10,
    CHAR_PROP_INDICATE           =0x20,
    CHAR_PROP_SIGNED_WRITE       =0x40,
    CHAR_PROP_EXT                =0x80
} CharacteristicProperty;

我可以用一些简单的东西来测试一组标志:

if ((propertiesMask & (CHAR_PROP_NOTIFY | CHAR_PROP_INDICATE)) != 0) ...

Swift 的替代方案可能看起来像

let properties:CBCharacteristicProperties = [.Write, .Read, .Indicate]
!properties.intersect([.Indicate, .Notify]).isEmpty

有没有更惯用的方法来做这个测试？不是的粉丝!在前面。但除此之外，看起来很简单，除了我真的对什么时候有交叉路口很感兴趣。这让我想添加我自己的。

extension OptionSetType {
    func hasIntersection(other:Self) -> Bool {
        return !self.intersect(other).isEmpty
    }
}

这让我可以写

properties.hasIntersection([.Indicate, .Notify])

是否有更好/更惯用的方法来做到这一点？我是不是自己滚而错过了什么？

Answer 1

OptionSetType 实现的协议(protocol) SetAlgebraType 中有这个方法:

isDisjointWith(_: Self) -> Bool

Returns true iff self.intersect(other).isEmpty.

因此您可以将测试缩短为:

!properties.isDisjointWith([.Indicate, .Notify])

或

properties.isDisjointWith([.Indicate, .Notify]) == false

您还可以将原始值与按位运算符进行比较，就像在 C 中所做的那样:

(properties.rawValue & (CharacteristicProperties.Notify.rawValue | CharacteristicProperties.Indicate.rawValue)) != 0

完整示例代码(在 playground 中):

struct CBCharacteristicProperties : OptionSetType {
  let rawValue: UInt
  init(rawValue: UInt) { self.rawValue = rawValue }

  static let Broadcast          = CBCharacteristicProperties(rawValue:0x01)
  static let Read               = CBCharacteristicProperties(rawValue:0x02)
  static let WriteWithoutResp   = CBCharacteristicProperties(rawValue:0x04)
  static let Write              = CBCharacteristicProperties(rawValue:0x08)
  static let Notify             = CBCharacteristicProperties(rawValue:0x10)
  static let Indicate           = CBCharacteristicProperties(rawValue:0x20)
  static let SignedWrite        = CBCharacteristicProperties(rawValue:0x40)
  static let Ext                = CBCharacteristicProperties(rawValue:0x80)
}

let properties = CBCharacteristicProperties([.Write, .Read, .Indicate])
print(!properties.intersect([.Indicate, .Notify]).isEmpty)
print(!properties.isDisjointWith([.Indicate, .Notify]))
print(properties.isDisjointWith([.Indicate, .Notify]) == false)
print((properties.rawValue & (CBCharacteristicProperties.Notify.rawValue | CBCharacteristicProperties.Indicate.rawValue)) != 0)

结果:

"true"
"true"
"true"
"true"