KCron

Cron realization for Kotlin Multiplatform

Features

• Kotlin Multiplatform library
• Parse Cron expressions
  • Include L, W, LW, '?' and #
• Build Cron expression by smart builder functions:

  builder
  .seconds(10 at 0) //Every 10 seconds starting at 0 seconds
  .minutes(5..25) // Every minute between 5 and 25
  .hours(5, 12) // Specific hours: 5 and 12
  .daysOfWeek(7 on 5) // On the 5th Sunday of the month
  .years(2050) // Specific year: 2050

• Build Cron expression via Kotlin style function:

  cron {
  seconds(10 at 0)//Every 10 seconds starting at 0 seconds
  minutes(5..25) // Every minute between 5 and 25
  hours(5, 12) // Specific hours: 5 and 12
  daysOfWeek(7 on 5) // On the 5th Sunday of the month
  years(2050) // Specific year: 2050
  }

• Support custom first week day

  val builder = Builder(WeekDays.Sunday)
  builder
  .daysOfWeek(7 on 5) // On the 5th Saturday of the month

• Parsing validation includes combination rules
  • 'days' and 'days of week' could not be setup simultaneously
• Support
  • JVM
  • Linux
  • Windows (mingwX64)
  • macOS
  • Javascript
  • iOS
• Support different DateTime libraries (via DateTime Provider Abstractions)

  Usage

  KCron-Common library as default implementation uses Kotlinx-DateTime library

  Add with Gradle

  kotlin {
  sourceSets {
      commonMain {
          dependencies {
              implementation 'com.ucasoft.kcron:kcron-common:0.14.4'
          }
      }
  }
  }

  Build Cron expression

  val builder = Cron.builder()
  // By default, builder contains any expression for every part
  println(builder.expression) // * * * ? * * *
  builder
  .seconds(10 at 0)
  .minutes(5..25)
  .hours(5, 12)
  .daysOfWeek(7 on 5)
  .years(2050)
  println(builder.expression) // 0/10 5-25 5,12 ? * 7#5 2050

  Parse as Classic as well as Modern Cron expressions

  // Auto detect
  val builder = Cron.parseAndBuild("0/10 5-25 5,12 ? * 7#5 2050") {
  it.firstDayOfWeek = WeekDays.Sunday
  }
  @OptIn(DelicateIterableApi::class)
  println(builder.asIterable().take(10))
  /* Result:
  [
  2050-01-29T05:05,
  2050-01-29T05:05:10,
  2050-01-29T05:05:20,
  2050-01-29T05:05:30,
  2050-01-29T05:05:40,
  2050-01-29T05:05:50,
  2050-01-29T05:06,
  2050-01-29T05:06:10,
  2050-01-29T05:06:20,
  2050-01-29T05:06:30
  ]
  */
  // OR Force to parse only Classic expressions
  try {
  val builder = Cron.parseAndBuild("0/10 5-25 5,12 ? * 7#5 2050") {
      it.version = Version.Classic
  }
  } catch(e: WrongCronExpression) {
  println(e.message) // Expression 0/10 5-25 5,12 ? * 7#5 2050 is not Classic Cron one!
  }

  Days of week and months can be defined in a parsed expression as numbers as well as short names

  builder = Cron.parseAndBuild("15/10 5-25 5 ? JAN,MAR 2,3,4,5 2050")
  println(builder.nextRun) // 2050-01-04T05:05:15
  // OR
  builder = Cron.parseAndBuild("15/10 5-25 5 ? 2-4 MON 2050")
  println(builder.nextRun) // 2050-02-07T05:05:15

  Easy change any part of expression

  val builder = Cron.parseAndBuild("0/10 5-25 5,12 ? * SUN#5 2050")
  builder.years(2021..2025)
  println(builder.expression) // 0/10 5-25 5,12 ? * SUN#5 2021-2025

  Current status

  This library is on beta version 0.14.4. It is continuing to develop. Check the news!