kotlin.UProgressionUtil.kt Maven / Gradle / Ivy
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/*
* Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
*/
package kotlin.internal
// (a - b) mod c
private fun differenceModulo(a: UInt, b: UInt, c: UInt): UInt {
val ac = a % c
val bc = b % c
return if (ac >= bc) ac - bc else ac - bc + c
}
private fun differenceModulo(a: ULong, b: ULong, c: ULong): ULong {
val ac = a % c
val bc = b % c
return if (ac >= bc) ac - bc else ac - bc + c
}
/**
* Calculates the final element of a bounded arithmetic progression, i.e. the last element of the progression which is in the range
* from [start] to [end] in case of a positive [step], or from [end] to [start] in case of a negative
* [step].
*
* No validation on passed parameters is performed. The given parameters should satisfy the condition:
*
* - either `step > 0` and `start <= end`,
* - or `step < 0` and `start >= end`.
*
* @param start first element of the progression
* @param end ending bound for the progression
* @param step increment, or difference of successive elements in the progression
* @return the final element of the progression
* @suppress
*/
@PublishedApi
@SinceKotlin("1.3")
internal fun getProgressionLastElement(start: UInt, end: UInt, step: Int): UInt = when {
step > 0 -> if (start >= end) end else end - differenceModulo(end, start, step.toUInt())
step < 0 -> if (start <= end) end else end + differenceModulo(start, end, (-step).toUInt())
else -> throw kotlin.IllegalArgumentException("Step is zero.")
}
/**
* Calculates the final element of a bounded arithmetic progression, i.e. the last element of the progression which is in the range
* from [start] to [end] in case of a positive [step], or from [end] to [start] in case of a negative
* [step].
*
* No validation on passed parameters is performed. The given parameters should satisfy the condition:
*
* - either `step > 0` and `start <= end`,
* - or `step < 0` and `start >= end`.
*
* @param start first element of the progression
* @param end ending bound for the progression
* @param step increment, or difference of successive elements in the progression
* @return the final element of the progression
* @suppress
*/
@PublishedApi
@SinceKotlin("1.3")
internal fun getProgressionLastElement(start: ULong, end: ULong, step: Long): ULong = when {
step > 0 -> if (start >= end) end else end - differenceModulo(end, start, step.toULong())
step < 0 -> if (start <= end) end else end + differenceModulo(start, end, (-step).toULong())
else -> throw kotlin.IllegalArgumentException("Step is zero.")
}