iOS: 学习笔记, Swift运算符定义

Swift操作符可以自行定义, 只需要加上简单的标志符即可.

@infix 中置运算. 如+,-,*,/运算

@prefix 前置运算. 如-

@postfix 后置运算. a++, a--

@assignment 赋值运算. +=, -=, --a, ++a

//

//  main.swift

//  SwiftBasic

//

//  Created by yao_yu on 14-7-27.

//  Copyright (c) 2014年 yao_yu. All rights reserved.

//



import Foundation



struct Vector2D{

    var x = 0.0, y = 0.0

}



@infix func +(a:Vector2D, b:Vector2D) -> Vector2D{

    return Vector2D(x: a.x + b.x, y: a.y + b.y)

}



@infix func -(a:Vector2D, b:Vector2D) -> Vector2D{

    return a + -b

}



@prefix func -(a: Vector2D) -> Vector2D{

    return Vector2D(x: -a.x, y: -a.y)

}



@assignment func += (inout a: Vector2D, b:Vector2D){

    a = a + b

}



@prefix @assignment func ++(inout a:Vector2D){

    ++a.x

    ++a.y

}



@postfix func ++(a: Vector2D) -> Vector2D{

    return a + Vector2D(x: 1, y: 1)

}



@infix func ==(a:Vector2D, b:Vector2D) -> Bool{

    return (a.x == b.x) && (a.y == b.y)

}



@infix func !=(a:Vector2D, b:Vector2D) -> Bool{

    return !(a == b)

}



func Vector2D_Test(){

    var a = Vector2D(x: 1, y: 2), b = Vector2D(x: 3, y: 5)

    var c = a + b

    a += b

    println("(\(c.x), \(c.y))")

    println("(\(a.x), \(a.y))")

    assert(a == c, "a == b失败")

    a += b

    assert(a != c, "a != b失败")

    c = a++

    println("(\(a.x), \(a.y))")

    println("(\(c.x), \(c.y))")

}





Vector2D_Test()