https://github.com/logicsquad/recurring
A Java implementation of the ideas in Martin Fowler's "Recurring Events for Calendars".
https://github.com/logicsquad/recurring
Last synced: 5 months ago
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A Java implementation of the ideas in Martin Fowler's "Recurring Events for Calendars".
- Host: GitHub
- URL: https://github.com/logicsquad/recurring
- Owner: logicsquad
- License: other
- Created: 2018-06-11T12:38:12.000Z (about 8 years ago)
- Default Branch: develop
- Last Pushed: 2024-01-05T10:45:27.000Z (over 2 years ago)
- Last Synced: 2025-08-22T12:22:21.704Z (10 months ago)
- Language: Java
- Size: 149 KB
- Stars: 10
- Watchers: 1
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE.txt
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README
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Recurring
=========
What is this?
-------------
This project provides some interfaces and classes to represent
_recurring events_ in Java. It is able to represent some simple
"temporal expressions", such as:
* First Thursday of the month
* Last Wednesday of the month
* Every day in June
* Every day from 17 May through 19 August
* 1 September
The expressions are agnostic to the _year_.
It also supports some simple ways of combining these expressions: union,
intersection and difference. These can be combined in arbitrarily
complex ways. For example:
* First Thursday and last Wednesday of every month from 17 May through
19 August, except the month of June
* Second Monday of January through March
Getting started
---------------
`ScheduleElement`s (which link a `TemporalExpression` to some object
representing an event) can be combined into a `Schedule`, which can
then answer queries about the elements it contains. For example,
construct a `TemporalExpression` representing an event that occurs on
the first Thursday and last Wednesday of every month, and then put a
`ScheduleElement` into a `Schedule`:
TemporalExpression firstThursday = DayInMonth.of(DayOfWeek.THURSDAY, 1);
TemporalExpression lastWednesday = DayInMonth.of(DayOfWeek.WEDNESDAY, -1);
ScheduleElement element = ScheduleElement.of("Meeting", Union.of(firstThursday, lastWednesday));
Schedule schedule = Schedule.of(element);
Among other things, the `Schedule` can now tell us if the meeting is on
today:
boolean today = schedule.isOccurring("Meeting", LocalDate.now());
when the meeting last occurred:
LocalDate last = schedule.previousOccurrence("Meeting", LocalDate.now());
and all future dates of the meeting:
Stream future = schedule.futureDates("Meeting", LocalDate.now());
Using Recurring
---------------
You can use Recurring in your projects by including it as a
dependency:
net.logicsquad
recurring
0.4
Note that _the API may change prior to a `1.0` release,_ at which time
it will remain stable, consistent with [semantic
versioning](https://semver.org).
Contributing
------------
By all means, open issue tickets and pull requests if you have something
to contribute.
References
----------
This project implements the ideas in [Martin Fowler's "Recurring Events
for Calendars"](https://martinfowler.com/apsupp/recurring.pdf) (1997).
Where appropriate, we have made some changes to the code and ideas
presented in the original article.
* We will make use of interfaces where appropriate. The original article
hinted at interfaces, but mostly gave examples of concrete classes.
* We will use `java.time.LocalDate` instead of `java.util.Date`.
* We will make some minor changes to suggested class names.
Most of this just reflects more modern Java idioms and changes in the
language and libraries.