Kotlin-31.オペレータ/演算子再負荷（operatooverload）
3559 ワード
公式文書:http://kotlinlang.org/docs/reference/operator-overloading.html
1.オペレータ再負荷（Operator overloading）
1.オペレータ再負荷（Operator overloading）
Kotlin !
( + - * /), precedence
member function extension function
operator
1. (Unary prefix operators)
+a a.unaryPlus()
-a a.unaryMinus()
!a a.not()
+a , :
a , T;
T operator unaryPlus(), T ;
, ;
R, +a R
: (Basic types), !
"-" :
data class Point(val x: Int, val y: Int)
operator fun Point.unaryMinus() = Point(-x, -y)
val point = Point(10, 20)
println(-point) // “(-10, -20)”
2. (Increments and decrements)
a++ a.inc()
a-- a.dec()
a++ ++a , ：
a , T;
T operator inc();
T ;
a++ :
a a0 ,
a.inc() a,
a0 .
++a :
a.inc() a，
a .
1. / (Arithmetic operators)
a + b a.plus(b)
a - b a.minus(b)
a * b a.times(b)
a / b a.div(b)
a % b a.rem(b), a.mod(b)( )
a..b a.rangeTo(b)
Kotlin 1.1 rem , mod (Kotlin 1.0)
:
// Counter "+"
data class Counter(val dayIndex: Int) {
operator fun plus(increment: Int): Counter {
return Counter(dayIndex + increment)
}
}
2.in ('In' operator)
a in b b.contains(a)
a !in b !b.contains(a)
3. (Indexed access operator)
a[i] a.get(i)
a[i, j] a.get(i, j)
a[i_1, ..., i_n] a.get(i_1, ..., i_n)
a[i] = b a.set(i, b)
a[i, j] = b a.set(i, j, b)
a[i_1, ..., i_n] = b a.set(i_1, ..., i_n, b)
4. (Invoke operator)
a() a.invoke()
a(i) a.invoke(i)
a(i, j) a.invoke(i, j)
a(i_1, ..., i_n) a.invoke(i_1, ..., i_n)
5. (Augmented assignment)
a += b a.plusAssign(b)
a -= b a.minusAssign(b)
a *= b a.timesAssign(b)
a /= b a.divAssign(b)
a %= b a.modAssign(b)
a += b, :
plus() , ( );
Unit, ;
a.plusAssign(b)
a = a + b ( a + b a )
: Kotlin !
6. (Equality and inequality operators)
a == b a?.equals(b) ?: (b === null)
a != b !(a?.equals(b) ?: (b === null))
: === !==( / ) , !
null == null true; x, x == null false
7. (Comparison operators)
( Int)
a > b a.compareTo(b) > 0
a < b a.compareTo(b) < 0
a >= b a.compareTo(b) >= 0
a <= b a.compareTo(b) <= 0