一个简单的解决方案是在您的类中实现Comparable接口。
我不是Kotlin的新手,我正在为我定义的自定义类进行运算符重载。该类称为“有理数”,代表有理数,例如117/1098。类的定义如下,我已经重载了一堆运算符,例如加号,减号,时间等等。但是我不确定如何重载“ in”运算符。
这是我的课程:
data class Rational(val rational: String) {
private val numerator: BigInteger
private val denominator: BigInteger
init {
val splitted = rational.split("/")
numerator = splitted[0].toBigInteger()
denominator = when (splitted[1]) {
"0" -> throw Exception("not allowed")
else -> splitted[1].toBigInteger()
}
}
operator fun plus(number: Rational): Rational {
val gcm = denominator * number.denominator
val numerator = (gcm / denominator) * numerator + (gcm / number.denominator) * number.numerator
return Rational("$numerator/$gcm")
}
operator fun minus(number: Rational): Rational {
val gcm = denominator * number.denominator
val numerator = (gcm / denominator) * numerator - (gcm / number.denominator) * number.numerator
return Rational("$numerator/$gcm")
}
operator fun times(number: Rational): Rational {
val numerator = numerator * number.numerator
val denominator = denominator * number.denominator
return Rational("$numerator/$denominator")
}
operator fun div(number: Rational): Rational {
val numerator = numerator * number.denominator
val denominator = denominator * number.numerator
return Rational("$numerator/$denominator")
}
operator fun compareTo(number: Rational): Int {
val ratio = this.numerator.toFloat() / this.denominator.toFloat()
val numberRatio = number.numerator.toFloat() / number.denominator.toFloat()
if (ratio > numberRatio) {
return 1
} else if (ratio == numberRatio) {
return 0
}
return -1
}
operator fun unaryMinus(): Rational {
val inverseNumerator = -numerator
return Rational("$inverseNumerator/$denominator")
}
operator fun unaryPlus(): Rational {
return Rational("$numerator/$denominator")
}
operator fun rangeTo(end: Rational): Any {
var range: MutableList<Rational> = arrayListOf()
val startNumerator = this.numerator.toInt()
val endNumerator = end.numerator.toInt()
var index = 0
if (this.denominator == end.denominator) {
for (i in startNumerator..endNumerator) {
range.add(index, Rational("$i/$denominator"))
}
}
return range
}
operator fun contains(number: Rational): Boolean {
if (this.denominator % number.denominator == 0.toBigInteger()
&& this.numerator <= number.numerator) {
return true
}
return false
}
override fun toString(): String {
val gcd = numerator.gcd(denominator)
return if (gcd != null) {
val newNumerator = numerator / gcd
val newDenominator = denominator / gcd
"$newNumerator/$newDenominator"
} else {
"$numerator/$denominator"
}
}
}
infix fun Int.divBy(denominator: Int): Rational {
if (denominator == 0) {
throw Exception("denominator 0 not allowed")
}
return Rational("$this/$denominator")
}
infix fun Long.divBy(denominator: Long): Rational {
if (denominator == 0L) {
throw Exception("denominator 0 not allowed")
}
return Rational("$this/$denominator")
}
infix fun BigInteger.divBy(denominator: BigInteger): Rational {
if (denominator == 0.toBigInteger()) {
throw Exception("denominator 0 not allowed")
}
return Rational("$this/$denominator")
}
fun String.toRational(): Rational {
return Rational(this)
}
这是我的主体,显然仍然无法编译:
fun main() {
val half = 1 divBy 2
val third = 1 divBy 3
val twoThirds = 2 divBy 3
println(half in third..twoThirds) // this line does not compile beacause in operator is not defined for the class
}
我想我必须重写“ rangeTo”运算符,但是我不确定该运算符的原型。我那里有人可以帮助我走上正确的路吗?
使in
工作的方法是使third..twoThirds
调用返回something,该方法具有contains(Rational)
方法,这是in
调用所转换的。
执行此操作的一种方法是在此处返回ClosedRange<Rational>
,如下所示:
operator fun rangeTo(end: Rational): ClosedRange<Rational> {
return object : ClosedRange<Rational> {
override val endInclusive: Rational = end
override val start: Rational = this@Rational
}
}
这对Rational
施加了类型约束,因为ClosedRange
需要实现ClosedRange
才能确定值是否属于其中。您可以通过实现Comparable
接口,然后将Comparable
添加到现有的Comparable
运算符中来进行此操作(此外,重命名参数以匹配该接口也是一种很好的做法):
operator
您也可以通过使用此实现来避免完全转换为浮点数,如@gidds在下面的注释中建议的那样:
compareTo
而且,您当前的compareTo
实现可能可能被丢弃,因为您不再需要它,并且它的功能很奇怪。
要在此处添加除直接答案之外的内容:如@Eugene Petrenko在其答案中建议的那样,除了使用data class Rational(val rational: String) : Comparable<Rational> {
...
override operator fun compareTo(other: Rational): Int {
val ratio = this.numerator.toFloat() / this.denominator.toFloat()
val numberRatio = other.numerator.toFloat() / other.denominator.toFloat()
if (ratio > numberRatio) {
return 1
} else if (ratio == numberRatio) {
return 0
}
return -1
}
}
的构造函数外,添加几个构造函数(例如,使用两个override operator fun compareTo(other: Rational): Int {
return (numerator * other.denominator - denominator * other.numerator).signum()
}
的构造函数)是可行的。 s,一个需要两个contains
。
String
运算符被声明为反。您需要在右侧带有左侧的扩展功能。
Int
例如,您缺少插入功能BigIntegers
,因此无法将in
浏览到https://kotlinlang.org/docs/reference/operator-overloading.html#in中>]
divBy
不是像
Int
这样的代码将起作用。从理论上讲,从Rational
开始为infix fun Int.divBy(i: Int) = Rational("$this/$i")
添加一个构造函数以避免解析。
val half = 1 divBy 2
类的Rational
方法中的返回类型错误,不应为Int
。应该声明为
rangeTo
现在带有
Rational
的示例应该可以使用。UPD:添加了RationalRange。我错过了重点,对不起。您完全不需要为
Any
类实现的data class RationalRange(val left: Rational, val right: Rational) { operator fun contains(r: Rational) = left <= r && r <= right } operator fun rangeTo(end: Rational): RationalRange(this, end)
函数。
x in a..b
的contains
函数不太可能使用Rational
,您可以直接用整数来实现
一个简单的解决方案是在您的类中实现Comparable接口。
compareTo
然后使用您的比较逻辑来实现compareTo()函数。
Rational
这将解决编译错误,而无需使用自定义逻辑覆盖rangeTo()函数。
一个简单的解决方案是在您的类中实现Comparable接口。