gocal

Fast (and opinionated) ICAL parser in Golang.

Gocal takes an io.Reader and produces an array of Events from it.

Event are parsed between two given dates (Gocal.Start and Gocal.End, 3 months by default). Any event outside this range will be ignored.

Usage

package main

import (
  "github.com/apognu/gocal"
)

func main() {
  f, _ := os.Open("/tmp/mycalendar.ics")
  defer f.Close()

  start, end := time.Now(), time.Now().Add(12*30*24*time.Hour)

  c := gocal.NewParser(f)
  c.Start, c.End = &start, &end
  c.Parse()

  for _, e := range c.Events {
    fmt.Printf("%s on %s by %s", e.Summary, e.Start, e.Organizer.Cn)
  }
}

Timezones

Timezones specified in TZID attributes are parsed and expected to be parsable by Go's time.LoadLocation() method. If you have an ICS file using some other form of representing timezones, you can specify the mapping to be used with a callback function:

var tzMapping = map[string]string{
	"My Super Zone": "Asia/Tokyo",
	"My Ultra Zone": "America/Los_Angeles",
}

gocal.SetTZMapper(func(s string) (*time.Location, error) {
  if tzid, ok := tzMapping[s]; ok {
    return time.LoadLocation(tzid)
  }
  return nil, fmt.Errorf("")
})

If this callback returns an error, the usual method of parsin the timezone will be tried. If both those methods fail, the date and time will be considered UTC.

Custom X-* properties

Any property starting with X- is considered a custom property and is unmarshalled in the event.CustomAttributes map of string to string. For instance, a X-LABEL would be accessible through event.CustomAttributes["X-LABEL"].

Recurring rules

Recurring rule are automatically parsed and expanded during the period set by Gocal.Start and Gocal.End.

That being said, I try to handle the most common situations for RRULEs, as well as overrides (EXDATEs and RECURRENCE-ID overrides).

This was tested only lightly, I might not cover all the cases.

Limitations

I do not pretend this abides by RFC 5545, this only covers parts I needed to be parsed for my own personal use. Among other, most property parameters are not handled by the library, and, for now, only the following properties are parsed:

• UID
• SUMMARY / DESCRIPTION
• DTSTART / DTEND (day-long, local, UTC and TZIDd)
• DTSTAMP / CREATED / LAST-MODIFIED
• LOCATION
• STATUS
• ORGANIZER (CN; DIR and value)
• ATTENDEEs (CN, DIR, PARTSTAT and value)
• ATTACH (FILENAME, ENCODING, VALUE, FMTTYPE and value)
• CATEGORIES
• GEO
• RRULE
• X-*

Also, we ignore whatever's not a VEVENT.