Allows parsing from general ISO8601 expressions, from the Date only representations to the Repetitions and Durations or periods.

https://en.wikipedia.org/wiki/ISO_8601

Does not support week dates yet.

To keep up to date with the most recent version:

go get github.com/jucardi/go-iso8601

To get a specific version:

go get gopkg.in/jucardi/go-iso8601.v1

To parse the representation of an ISO8601 string simply use the Parse function.

Given the following expression

exp := "R5/2008-03-01T13:00:00Z/P1Y2M10DT2H30M/2017-03-01T13:00:00Z"

Where:

• R5 represents 5 repetitions
• 2008-03-01T13:00:00Z represents a start date in UTC
• P1Y2M10DT2H30M represents an interval or duration
• 2017-03-01T13:00:00Z represents an end date in UTC

result, err := iso8601.Parse(exp)

The Parse function will return a struct representing the ISO8601 expression, which will be equal to:

result := &IntervalDescriptor {
	Start:   startTime, // a time.Time struct obtained by parsing the start date string
	End:     endTime,   // a time.Time struct obtained by parsing the end date string
	Repeats: 5,         // Equal to what was indicated in the Rn portion of the string
	Period: &Period{    // Struct containing the values defined by the interval or duration portion of the string
		Years:   1,
		Months:  2,
		Days:    10,
		Hours:   2,
		Minutes: 30,
		Seconds: 0,
	}
}

By having a defined IntervalDescriptor struct, simply by doing a .ToString(), will return the string representation of the struct in ISO8601 format.

Works similar to it's parent IntervalDecriptor, a Period may be created from scratch or may be obtained by using the PeriodFromString function and passing a Period representation of the ISO8601.

The Period struct provides additional utility functions.

• Normalize: If a period has values that can be converted into a greater full unit, it will do so. For example, if a period has 100 seconds, by invoking Normalize, Seconds will be set to 40 and the whole minute subtracted from the seconds amount will be added to the Minutes value.
• ToDuration: Converts the struct into a time.Duration representation to easily be used with the structs in the time package.
• HasTime: Indicates whether the period has any time values (Hours, Minutes or Seconds).