SpringCronEvaluator.kt

import org.springframework.scheduling.support.CronExpression
import java.time.LocalDateTime
import java.time.LocalDateTime.now

/**
 * Let Spring generate a sequence of dates according top the provided cron string.
 * See: https://spring.io/blog/2020/11/10/new-in-spring-5-3-improved-cron-expressions
 */
fun genTimes(cronStr: String): Sequence<LocalDateTime> =
    CronExpression.parse(cronStr).let { exp ->
        generateSequence(now()) { t -> exp.next(t) }
    }

fun main() {
    genTimes("0 * * * * *")
        .take(10)
        .forEach { println(it) }
}