rrule-go

Go library for working with recurrence rules for calendar dates.

The rrule module offers a complete implementation of the recurrence rules documented in the iCalendar RFC. It is a partial port of the rrule module from the excellent python-dateutil library.

Demo

rrule.RRule

package main

import (
  "fmt"
  "time"

  "github.com/teambition/rrule-go"
)

func printTimeSlice(ts []time.Time) {
    for _, t := range ts {
        fmt.Println(t)
    }
}

func main() {
    // Daily, for 10 occurrences.
    r, _ := rrule.NewRRule(rrule.ROption{
        Freq:    rrule.DAILY,
        Count:   10,
        Dtstart: time.Date(1997, 9, 2, 9, 0, 0, 0, time.UTC),
    })

    fmt.Println(r.String())
    // DTSTART:19970902T090000Z
    // RRULE:FREQ=DAILY;COUNT=10

    printTimeSlice(r.All())
    // 1997-09-02 09:00:00 +0000 UTC
    // 1997-09-03 09:00:00 +0000 UTC
    // ...
    // 1997-09-07 09:00:00 +0000 UTC

    printTimeSlice(r.Between(
        time.Date(1997, 9, 6, 0, 0, 0, 0, time.UTC),
        time.Date(1997, 9, 8, 0, 0, 0, 0, time.UTC), true))
    // [1997-09-06 09:00:00 +0000 UTC
    //  1997-09-07 09:00:00 +0000 UTC]

    // Every four years, the first Tuesday after a Monday in November, 3 occurrences (U.S. Presidential Election day).
    r, _ = rrule.NewRRule(rrule.ROption{
        Freq:       rrule.YEARLY,
        Interval:   4,
        Count:      3,
        Bymonth:    []int{11},
        Byweekday:  []rrule.Weekday{rrule.TU},
        Bymonthday: []int{2, 3, 4, 5, 6, 7, 8},
        Dtstart:    time.Date(1996, 11, 5, 9, 0, 0, 0, time.UTC),
    })

    fmt.Println(r.String())
    // DTSTART:19961105T090000Z
    // RRULE:FREQ=YEARLY;INTERVAL=4;COUNT=3;BYMONTH=11;BYMONTHDAY=2,3,4,5,6,7,8;BYDAY=TU

    printTimeSlice(r.All())
    // 1996-11-05 09:00:00 +0000 UTC
    // 2000-11-07 09:00:00 +0000 UTC
    // 2004-11-02 09:00:00 +0000 UTC
}

rrule.Set

func ExampleSet() {
    // Daily, for 7 days, jumping Saturday and Sunday occurrences.
    set := rrule.Set{}
    r, _ := rrule.NewRRule(rrule.ROption{
        Freq:    rrule.DAILY,
        Count:   7,
        Dtstart: time.Date(1997, 9, 2, 9, 0, 0, 0, time.UTC)})
    set.RRule(r)

    fmt.Println(set.String())
    // DTSTART:19970902T090000Z
    // RRULE:FREQ=DAILY;COUNT=7

    printTimeSlice(set.All())
    // 1997-09-02 09:00:00 +0000 UTC
    // 1997-09-03 09:00:00 +0000 UTC
    // 1997-09-04 09:00:00 +0000 UTC
    // 1997-09-05 09:00:00 +0000 UTC
    // 1997-09-06 09:00:00 +0000 UTC
    // 1997-09-07 09:00:00 +0000 UTC
    // 1997-09-08 09:00:00 +0000 UTC

    // Weekly, for 4 weeks, plus one time on day 7, and not on day 16.
    set = rrule.Set{}
    r, _ = rrule.NewRRule(rrule.ROption{
        Freq:    rrule.WEEKLY,
        Count:   4,
        Dtstart: time.Date(1997, 9, 2, 9, 0, 0, 0, time.UTC)})
    set.RRule(r)
    set.RDate(time.Date(1997, 9, 7, 9, 0, 0, 0, time.UTC))
    set.ExDate(time.Date(1997, 9, 16, 9, 0, 0, 0, time.UTC))

    fmt.Println(set.String())
    // DTSTART:19970902T090000Z
    // RRULE:FREQ=WEEKLY;COUNT=4
    // RDATE:19970907T090000Z
    // EXDATE:19970916T090000Z

    printTimeSlice(set.All())
    // 1997-09-02 09:00:00 +0000 UTC
    // 1997-09-07 09:00:00 +0000 UTC
    // 1997-09-09 09:00:00 +0000 UTC
    // 1997-09-23 09:00:00 +0000 UTC
}

rrule.StrToRRule

func ExampleStrToRRule() {
    // Compatible with old DTSTART
    r, _ := rrule.StrToRRule("FREQ=DAILY;DTSTART=20060101T150405Z;COUNT=5")
    fmt.Println(r.OrigOptions.RRuleString())
    // FREQ=DAILY;COUNT=5

    fmt.Println(r.OrigOptions.String())
    // DTSTART:20060101T150405Z
    // RRULE:FREQ=DAILY;COUNT=5

    fmt.Println(r.String())
    // DTSTART:20060101T150405Z
    // RRULE:FREQ=DAILY;COUNT=5

    printTimeSlice(r.All())
    // 2006-01-01 15:04:05 +0000 UTC
    // 2006-01-02 15:04:05 +0000 UTC
    // 2006-01-03 15:04:05 +0000 UTC
    // 2006-01-04 15:04:05 +0000 UTC
    // 2006-01-05 15:04:05 +0000 UTC
}

rrule.StrToRRuleSet

func ExampleStrToRRuleSet() {
    s, _ := rrule.StrToRRuleSet("DTSTART:20060101T150405Z\nRRULE:FREQ=DAILY;COUNT=5\nEXDATE:20060102T150405Z")
    fmt.Println(s.String())
    // DTSTART:20060101T150405Z
    // RRULE:FREQ=DAILY;COUNT=5
    // EXDATE:20060102T150405Z

    printTimeSlice(s.All())
    // 2006-01-01 15:04:05 +0000 UTC
    // 2006-01-03 15:04:05 +0000 UTC
    // 2006-01-04 15:04:05 +0000 UTC
    // 2006-01-05 15:04:05 +0000 UTC
}

For more examples see python-dateutil documentation.

teambition / rrule-go

readme