Sha256: 471d1d7d23d945e0bbe7b88150ff3ffc2e742ba2cd7ce7fc434b0273d43db1d8
Contents?: true
Size: 1.01 KB
Versions: 125
Compression:
Stored size: 1.01 KB
Contents
data class Luhn(val number: Long) {
val checkDigit: Int by lazy { checkDigit(number) }
val addends: List<Int> by lazy {
digits(number).withIndex().reversed()
.map { if (isOdd(it.index)) dbl(it.value) else it.value }
}
val checksum: Int by lazy { addends.sum() }
val isValid: Boolean by lazy { checksum % 10 == 0 }
val create: Long by lazy {
val zeroCheckDigitNumber = number * 10
val luhn = Luhn(zeroCheckDigitNumber)
if (luhn.isValid) zeroCheckDigitNumber else zeroCheckDigitNumber + (10 - luhn.checksum % 10)
}
companion object {
private fun checkDigit(n: Long) = (n % 10).toInt()
private fun digits(n: Long): List<Int> = when (n) {
0L -> emptyList()
else -> listOf(checkDigit(n)) + digits(n / 10)
}
private fun dbl(n: Int): Int {
val dbled = n * 2
return if (dbled > 10) dbled - 9 else dbled
}
private fun isOdd(i: Int) = i % 2 == 1
}
}
Version data entries
125 entries across 125 versions & 1 rubygems