A performant rust implementation of recurrence rules as defined in the iCalendar RFC.

RRule provides two types for working with recurrence rules:

• RRule: For working with a single recurrence rule without any exception dates (exdates / exrules) and no additional dates (rdate).
• RRuleSet: For working with a collection of rrules, exrules, rdates and exdates. Both the rrule and exrule properties are represented by the RRule type and the rdate and exdate properties are represented by the DateTime type provided by the chrono and chrono-tz crates.

Building RRule and RRuleSet

Both types implements the std::str::FromStr trait so that they can be parsed and built from a string representation. RRule can additionally be constructed from the Option type which help build the recurrence rule. RRuleSet can also be built by composing multiple RRules for its rrule and exrule properties and DateTime for its exdate and rdate properties. See the examples below.

Generating occurrences

RRule and RRuleSet both implement DateFilter which implements methods for easy filtering:

• all: Generate all recurrences that matches the rules (with a limit to prevent infinite loops).
• all_between: Generate all recurrences that matches the rules and are between two given dates.
• just_before: Generate the last recurrence that matches the rules and is before a given date.
• just_after: Generate the first recurrence that matches the rules and is after a given date.
• ...

If you have some additional filters or want to work with infinite recurrence rules both RRule and RRuleSet implements the Iterator traits which makes them very flexible. All the methods above uses the iterator trait in its implementation as shown below.

use chrono::{DateTime, TimeZone};
use chrono_tz::UTC;
use rrule::{DateFilter, RRule};

let rrule: RRule = "DTSTART:20120201T093000Z\nRRULE:FREQ=DAILY;COUNT=3".parse().unwrap();

// All dates
assert_eq!(
vec![
DateTime::parse_from_rfc3339("2012-02-01T09:30:00+00:00").unwrap(),
DateTime::parse_from_rfc3339("2012-02-02T09:30:00+00:00").unwrap(),
DateTime::parse_from_rfc3339("2012-02-03T09:30:00+00:00").unwrap(),
],
rrule.all(100).unwrap()
);

Find all events that are within a given range.

# use chrono::{DateTime, TimeZone};
# use chrono_tz::UTC;
# use rrule::{DateFilter, RRule};
#
let rrule: RRule = "DTSTART:20120201T093000Z\nRRULE:FREQ=DAILY;COUNT=3".parse().unwrap();
// Between two dates
let after = UTC.ymd(2012, 2, 1).and_hms(10, 0, 0);
let before = UTC.ymd(2012, 4, 1).and_hms(9, 0, 0);
let inc = true; // Whether dates equal to after or before should be added;

assert_eq!(
vec![
DateTime::parse_from_rfc3339("2012-02-02T09:30:00+00:00").unwrap(),
DateTime::parse_from_rfc3339("2012-02-03T09:30:00+00:00").unwrap(),
],
rrule.all_between(after, before, inc).unwrap()
);

Note: All the generated recurrence will be in the same time zone as the dt_start property.

Example

Quick start by parsing strings

use chrono::DateTime;
use rrule::{DateFilter, RRule};

// Parse a RRule string
let rrule: RRule = "DTSTART:20120201T093000Z\n\
RRULE:FREQ=WEEKLY;INTERVAL=5;UNTIL=20130130T230000Z;BYDAY=MO,FR".parse().unwrap();
assert_eq!(rrule.all(100).unwrap().len(), 21);

use rrule::RRuleSet;

// Parse a RRuleSet string
let rrule_set: RRuleSet = "DTSTART:20120201T023000Z\n\
RRULE:FREQ=MONTHLY;COUNT=5\n\
RDATE:20120701T023000Z,20120702T023000Z\n\
EXRULE:FREQ=MONTHLY;COUNT=2\n\
EXDATE:20120601T023000Z".parse().unwrap();
let all_dates = rrule_set.all(100).unwrap();
assert_eq!(all_dates.len(), 4);

assert_eq!(
vec![
DateTime::parse_from_rfc3339("2012-04-01T02:30:00+00:00").unwrap(),
DateTime::parse_from_rfc3339("2012-05-01T02:30:00+00:00").unwrap(),
DateTime::parse_from_rfc3339("2012-07-01T02:30:00+00:00").unwrap(),
DateTime::parse_from_rfc3339("2012-07-02T02:30:00+00:00").unwrap(),
],
all_dates
);