swift - Swift3 中的范围

Question

我正在努力应对 Swift3 的一项更改。早些时候他们治疗了...和..<如Range ，但现在他们有大量新的“子范围”。我想要一个接受两个范围变体的函数。

struct Test {
  var data = [1,2,3,4,5]
  subscript(r:Range<Int>) -> [Int] {
    return Array(data[r])
  }
}
let t = Test()
print(t[0...1]) // fails because now this is a ClosedRange
print(t[0..<2])

我想要一个

  subscript(r:TakesAnyRange<Int>) -> [Int] {

Answer 1

您可以通过使用 CountableRange 和 CountableClosedRange 来避免重复，因为其中一个可以转换为另一个:

struct Test {
  var data = [1,2,3,4,5]

  subscript(r: CountableRange<Int>) -> [Int] {
    return Array(data[r])
  }

  subscript(r: CountableClosedRange<Int>) -> [Int] {
    return self[CountableRange(r)]
  }
}

这适用于 Int 范围，这是您在问题中指定的范围。来自苹果文档:

You can create a countable range over any type that conforms to the Strideable protocol and uses an integer as its associated Stride type. By default, Swift’s integer and pointer types are usable as the bounds of a countable range.