kotlin.internal.progressionUtil.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2018 JetBrains s.r.o. 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 mod b (in arithmetical sense)
private fun mod(a: Int, b: Int): Int {
val mod = a % b
return if (mod >= 0) mod else mod + b
}
private fun mod(a: Long, b: Long): Long {
val mod = a % b
return if (mod >= 0) mod else mod + b
}
// (a - b) mod c
private fun differenceModulo(a: Int, b: Int, c: Int): Int {
return mod(mod(a, c) - mod(b, c), c)
}
private fun differenceModulo(a: Long, b: Long, c: Long): Long {
return mod(mod(a, c) - mod(b, c), 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
internal fun getProgressionLastElement(start: Int, end: Int, step: Int): Int = when {
step > 0 -> if (start >= end) end else end - differenceModulo(end, start, step)
step < 0 -> if (start <= end) end else end + differenceModulo(start, end, -step)
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
internal fun getProgressionLastElement(start: Long, end: Long, step: Long): Long = when {
step > 0 -> if (start >= end) end else end - differenceModulo(end, start, step)
step < 0 -> if (start <= end) end else end + differenceModulo(start, end, -step)
else -> throw kotlin.IllegalArgumentException("Step is zero.")
}