Crate rrule

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

RRule provides two main types for working with recurrence rules:

• RRule: For working with a single recurrence rule without any exception dates (exdates / exrules) and no additonal 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 types

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

Interface

RRule and RRuleSet have the same interface for generating recurrences. The four methods for "querying" recurrences are:

• all: Generate all recurrences that matches the rules
• between: Generate all recurrences that matches the rules and are between two given dates
• before: Generate the last recurrence that matches the rules and is before a given date
• after: Generate the first recurrence that matches the rules and is after a given date

Examples

Quick start by parsing strings

extern crate rrule;

use rrule::RRule;

// Parse a RRule string, return a RRul to get e type
let mut rrule: RRule = "DTSTART:20120201T093000Z\nRRULE:FREQ=WEEKLY;INTERVAL=5;UNTIL=20130130T230000Z;BYDAY=MO,FR".parse().unwrap();
assert_eq!(rrule.all().len(), 21);


use rrule::RRuleSet;

// Parse a RRuleSet string, return a RRuleSet type
let mut rrule_set: RRuleSet = "DTSTART:20120201T023000Z\nRRULE:FREQ=MONTHLY;COUNT=5\nRDATE:20120701T023000Z,20120702T023000Z\nEXRULE:FREQ=MONTHLY;COUNT=2\nEXDATE:20120601T023000Z".parse().unwrap();
assert_eq!(rrule_set.all().len(), 4);

Using Options to build RRule

extern crate rrule;
extern crate chrono;
extern crate chrono_tz;

use chrono::prelude::*;
use chrono_tz::UTC;
use rrule::{RRule, Options, Frequenzy, Weekday};

// Build options that starts first day in 2020 at 9:00AM and occurs daily 5 times
let mut options = Options::new()
    .dtstart(UTC.ymd(2020, 1, 1).and_hms(9, 0, 0))
    .count(5)
    .freq(Frequenzy::Daily)
    .build()
    .unwrap();

// Construct `RRule` from options
let mut rrule = RRule::new(options);
let recurrences = rrule.all();
for i in 0..5 {
    assert_eq!(recurrences[i].year(), 2020);
    assert_eq!(recurrences[i].month(), 1);
    assert_eq!(recurrences[i].day(), 1 + i as u32);
    assert_eq!(recurrences[i].hour(), 9);
}
assert_eq!(recurrences.len(), 5);

Construct RRuleSet from one rrule and exrule. The rrule will occur weekly on Tuesday and Wednesday and the exrule will occur weekly on Wednesday, and therefore the end result will contain weekly recurrences just on Wednesday.

extern crate rrule;
extern crate chrono;
extern crate chrono_tz;

use chrono::prelude::*;
use chrono_tz::UTC;
use rrule::{RRule, RRuleSet, Options, Frequenzy, Weekday};


// Build options for rrule that occurs weekly on Tuesday and Wednesday
let mut rrule_options = Options::new()
    .dtstart(UTC.ymd(2020, 1, 1).and_hms(9, 0, 0))
    .count(4)
    .freq(Frequenzy::Weekly)
    .byweekday(vec![Weekday::Tue, Weekday::Wed])
    .build()
    .unwrap();

// Construct `RRule` from options
let mut rrule = RRule::new(rrule_options);


// Build options for exrule that occurs weekly on Wednesday
let mut exrule_options = Options::new()
    .dtstart(UTC.ymd(2020, 1, 1).and_hms(9, 0, 0))
    .count(4)
    .freq(Frequenzy::Weekly)
    .byweekday(vec![Weekday::Wed])
    .build()
    .unwrap();

// Construct `RRule` from options
let mut exrule = RRule::new(exrule_options);

// Now create the RRuleSet and add rrule and exrule
let mut rrule_set = RRuleSet::new();
rrule_set.rrule(rrule);
rrule_set.exrule(exrule);

let recurrences = rrule_set.all();
 
// Check that all the recurrences are on a Tuesday
for occurence in &recurrences {
    assert_eq!(occurence.weekday(), Weekday::Tue);
}

assert_eq!(recurrences.len(), 2);

Timezone support

extern crate rrule;
extern crate chrono;
extern crate chrono_tz;

use chrono::prelude::*;
use chrono_tz::{UTC, Tz};
use chrono_tz::Europe::Berlin;
use rrule::{RRule, RRuleSet, Options, Frequenzy, Weekday};

// SOME NOTES:
// recurrences produced by an rrule will be in the same timezone
// as the start datetime provided (dtstart). The `until` datetime MUST
// always be specified with the UTC timezone if it is specified.

// Example:
// The following examples uses the RRuleSet type with an RRule that yields recurrences
// in the Europe/Berlin timezone, and one EXDATE that is specified
// in UTC and collides (and therefore filters away) with one of those recurrences.  


// Build options for rrule that occurs daily at 9 oclock for 4 times
let mut rrule_options = Options::new()
    .dtstart(Berlin.ymd(2020, 1, 1).and_hms(9, 0, 0))
    .count(4)
    .freq(Frequenzy::Daily)
    .build()
    .unwrap();

let mut rrule = RRule::new(rrule_options);

// Exdate in the UTC at 8 oclock which is 9 oclock in Berlin and therefore
// collides with the second rrule occurence.
let exdate = UTC.ymd(2020, 1, 2).and_hms(8, 0, 0);

// Now create the RRuleSet and add rrule and exdate
let mut rrule_set = RRuleSet::new();
rrule_set.rrule(rrule);
rrule_set.exdate(exdate);

let recurrences = rrule_set.all();
// RRule contained 4 recurrences but 1 was filtered away by the exdate
assert_eq!(recurrences.len(), 3);

// If you want to get back the DateTimes in another timezone you can just iterate over the result
// and convert them to another timezone by using the with_timzone method provided by the DateTime type.
// Refer to the chrono and chrono-tz crates for more documenation on working with the DateTime type.

// Example of converting to mocow timezone
use chrono_tz::Europe::Moscow;

let recurrences_in_moscow_tz: Vec<DateTime<Tz>> = recurrences.iter()
    .map(|d| d.with_timezone(&Moscow)).collect();


// Example of converting to local timezone (Local comes from chrono::prelude::*)
let recurrences_in_local_tz: Vec<DateTime<Local>> = recurrences.iter()
    .map(|d| d.with_timezone(&Local)).collect();

Structs

Options
ParsedOptions
RRule
RRuleSet

Enums

Frequenzy
Weekday	The day of week.