/* Advanced Operators -> 更新到XCode Beta5
1.默认运算是不可以溢出的，否则报错。
如果是故意溢出，但是swift提供了一组已&开头的运算符 &+可以溢出。
5个可溢出操作 &+ &- &* &/(除0操作返回0) &%
var a:UInt8 = 255 &+ 1; //结果为0
✨✨var a:UInt8 = 300 &+ 1;这个算式编译会报错，因为swift自动推倒类型后，
后面两个加法都是UInt8的，300范围外，会报如下错误：
Integer literal overflows when stored int UInt8.(即当把300存到Uint8时出错)
2.操作符重载
中缀运算符如+-等不需要特殊标示，混合赋值语句 +＝ 也不需要加特殊标示
前置++用 prefix 后置++用postfix；注意新版本中去掉了@，＝运算符不再需要assignment修饰
前置的还有一种情况就是只有一个+或者减号
3.自定义新的运算符需要先声明再定义，声明中需要infix，prefix，postfix说明，定义中infix不需要。
一元运算符需要指明前置，和后置，括号中的结合性，优先级不需要指定。
infix operator +- { associativity left precedence 140 } //声明
func +- (l, r){} //定义
*/
//Bitwise operator
let temp:UInt8 = 0b00001111
//NOT 按位取反
println("~temp: \(~temp)")//0b11110000
//Bitwise And 按位与
println(temp & (~temp))//0b00000000
//Bitwise OR 按位或
println(temp | (~temp))//0b11111111
//Bitwise XOR 按位异或 ^
//Bitwise Left and Right Shift Operators << >>
//无符号数左右移动后补零
//有符号数最高位保持不变，其余位左移动时右边补零，右移动时负数补1正数补 0
//操作符重载,这里conform Printable协议，可以用println直接输出。
struct Vector2D: Printable
{
var x = 0.0, y = 0.0
// Printable协议
var description:String {
get {
return "x: \(x), y: \(y)"
}
}
}
//+
func + (l: Vector2D, r: Vector2D) -> Vector2D
{
return Vector2D(x: l.x + r.x, y: l.y + r.y)
}
//-
func - (l: Vector2D, r: Vector2D) -> Vector2D
{
return Vector2D(x: l.x - r.x, y: l.y - r.y)
}
//postfix ++ 并且实现赋值功能
postfix func ++ (inout v: Vector2D) -> Vector2D
{
return Vector2D(x: v.x++, y: v.y++)
}
//prefix ++
prefix func ++ (inout v: Vector2D) -> Vector2D
{
return Vector2D(x: ++v.x, y: ++v.y)
}
//prefix -
prefix func - (inout v: Vector2D) -> Vector2D
{
return Vector2D(x: -v.x, y: -v.y)
}
//==
func == (l: Vector2D, r: Vector2D) -> Bool
{
return ( (l.x == l.x) && (l.y == r.y) ) ? true : false;
}
//!=
func != (l: Vector2D, r: Vector2D) -> Bool
{
return ( (l.x == l.x) && (l.y == r.y) ) ? false : true;
}
func += (inout l:Vector2D, r:Vector2D)
{
l = l + r//这里可以直接用前面实现的加法运算；a += b; a 是第一个左参数，b是第二个右参数
}
var v1 = Vector2D(x:1.0, y:3.0)
var v2 = Vector2D(x:1.0, y:1.0)
println("v1+v2: \(v1+v2)")
var v3 = v2 + ++v1
println("v2 + ++v1 : \(v3)")
println(v1)
v1 = Vector2D(x:1.0, y:3.0)
v3 = v2 + v1++
println(v3)
println(v1)
//可以自定义符号， = - + * % < > ! & | ^ . ~,开头的符号即可。
//新符号定义前需要声明✨✨，声明中需要用infix，prefix，postfix符号
infix operator +- { associativity left precedence 140 }
//当定义前置和后置运算符时，｛｝中的内容不可以定义，默认为最高级别的。
func +- (l:Vector2D, r: Vector2D) ->Vector2D
{
return Vector2D(x: l.x + r.x, y: l.y - r.y)
}
//定义的时候不需要用infix，声明的时候需要。
/*Language Reference->Expression->Binary Expressions的介绍
Exponentiative (No associativity, precedence level 160)
<< Bitwise left shift
>> Bitwise right shift
Multiplicative (Left associative, precedence level 150)
* Multiply
/ Divide
% Remainder
&* Multiply, ignoring overflow
&/ Divide, ignoring overflow
&% Remainder, ignoring overflow
& Bitwise AND
Additive (Left associative, precedence level 140)
+ Add
- Subtract
&+ Add with overflow
&- Subtract with overflow
| Bitwise OR
^ Bitwise XOR
Range (No associativity, precedence level 135)
..< Half-open range
... Closed range
Cast (No associativity, precedence level 132)
is Type check
as Type cast
Comparative (No associativity, precedence level 130)
< Less than
<= Less than or equal
> Greater than
>= Greater than or equal
== Equal
!= Not equal
=== Identical
!== Not identical
~= Pattern match
Conjunctive (Left associative, precedence level 120)
&& Logical AND
Disjunctive (Left associative, precedence level 110)
|| Logical OR
Nil Coalescing (Right associative, precedence level 110)
?? Nil coalescing
Ternary Conditional (Right associative, precedence level 100)
?: Ternary conditional
Assignment (Right associative, precedence level 90)
= Assign
*= Multiply and assign
/= Divide and assign
%= Remainder and assign
+= Add and assign
-= Subtract and assign
<<= Left bit shift and assign
>>= Right bit shift and assign
&= Bitwise AND and assign
^= Bitwise XOR and assign
|= Bitwise OR and assign
&&= Logical AND and assign
||= Logical OR and assign
*/
//《完》
