Swift心得笔记之运算符

var a: String? = "a"
var b: String? = "b"
var c = a ?? b   // "a"
a = nil
c = a ?? b     // "b"
b = nil
c = a ?? b ?? "c"  // "c"

infix operator ||| {}

func |||<T> (left: T?, right: T) -> T {
  if let l = left { 
    return l 
  }
  return right
}

var a:String?
var b = "b"
var c = a ||| b

switch aNumber
{
case 0...5:
  println("This number is between 0 and 5")
case 6...10:
  println("This number is between 6 and 10")
default:
  println("This number is not between 0 and 10")
}

infix operator .. { associativity none precedence 135}

func .. (lhs: Int, rhs: Int) -> Range<Int> {
  return lhs..<rhs
}

for i in 0..10 {
  println("index \(i)")
}

var range = 1...4
var generator = range.generate()  // {startIndex 1, endIndex 5}
generator.next() // 1
generator.next() // 2
generator.next() // 3
generator.next() // 4
generator.next() // nil

let test = "Hello"
let interval = "a"..."z"

for c in test {
  if interval.contains(String(c)) {
    println("\(c)")
  }
}

2.1.3 :001 > a="abc"
 => "abc"
2.1.3 :002 > a[0]
 => "a"
2.1.3 :003 > a[0..1]
 => "ab"

extension String {
  subscript (r: Range<Int>) -> String {
    get {
      let startIndex = advance(self.startIndex, r.startIndex)
      let endIndex = advance(startIndex, r.endIndex - r.startIndex)

      return self[Range(start: startIndex, end: endIndex)]
    }
  }
}

var s = "Hello, playground"

println(s[0...5]) // ==> "Hello,"
println(s[0..<5]) // ==> "Hello"

let name = "Joris Kluivers"

let start = name.startIndex
let end = find(name, " ")

if (end != nil) {
  let firstName = name[start..<end!]
} else {
  // no space found
}