defn

Value Members

package crontab

Provides utilities for working with crontab time and date specifications.

Crontab

Provides utilities for working with crontab time and date specifications.

Overview

The main class to use is Spec. It can be used to instantiate valid crontab specs and to generate and match upcoming datetimes that match it. Its companion object provides a method that can be used to parse crontab specifications.

Parsing

On success, a Right value containing the Spec is returned:

scala> val Right(c) = Spec.parse("* * * * *")
c: Spec = Spec(Every(), Every(), Every(), Every(), Every())

On failure, a Left value containing a parse error is returned:

scala> val Left(error) = Spec.parse("foo")
error: String =
Invalid input 'f', expected a spec like '0 * * * Sun' or a named rule like '@daily' (line 1, column 1):
foo
^

Spec usage

Specs can be used to generate upcoming dates that match from a given start time (defaults to the current time + 1 minute):

scala> import io.defn.crontab._
import io.defn.crontab._

scala> val Right(spec) = Spec.parse("0-59/2 * * * *")
spec: io.defn.crontab.Spec = Spec(Range(Minute(0),Minute(59),2),Every(),Every(),Every(),Every())

scala> spec.dateTimes.take(2).toList.foreach(println _)
2017-01-17T12:38+02:00[Europe/Bucharest]
2017-01-17T12:40+02:00[Europe/Bucharest]
res0: ()

They can also be used to check if specific dates match:

scala> import io.defn.crontab._
import io.defn.crontab._

scala> import java.time.{LocalDateTime, ZoneId}
import java.time.{LocalDateTime, ZoneId}

scala> val now = LocalDateTime.now()
now: java.time.LocalDateTime = 2017-01-17T12:38:47.704

scala> now.getDayOfWeek()
res0: java.time.DayOfWeek = TUESDAY

scala> val Right(spec) = Spec.parse("* * * * Sun")
spec: io.defn.crontab.Spec = Spec(Every(),Every(),Every(),Every(),Exact(Sun))

scala> spec.matches(now.atZone(ZoneId.of("UTC")))
res1: Boolean = false

scala> spec.matches(now.plusDays(5).atZone(ZoneId.of("UTC")))
res2: Boolean = true

Warning

It is possible for certain specs to cause dateTimes to loop infinitely (i.e. when no upcoming date times match the spec) so handle user-input specs with extra care.

package defn