Chronic

Chronic is a natural language date/time parser written in pure Ruby. See below for the wide variety of formats Chronic will parse.

Installation

$ gem install chronic

Usage

require 'chronic'

Time.now   #=> Sun Aug 27 23:18:25 PDT 2006

Chronic.parse('tomorrow')
  #=> Mon Aug 28 12:00:00 PDT 2006

Chronic.parse('monday', :context => :past)
  #=> Mon Aug 21 12:00:00 PDT 2006

Chronic.parse('this tuesday 5:00')
  #=> Tue Aug 29 17:00:00 PDT 2006

Chronic.parse('this tuesday 5:00', :ambiguous_time_range => :none)
  #=> Tue Aug 29 05:00:00 PDT 2006

Chronic.parse('may 27th', :now => Time.local(2000, 1, 1))
  #=> Sat May 27 12:00:00 PDT 2000

Chronic.parse('may 27th', :guess => false)
  #=> Sun May 27 00:00:00 PDT 2007..Mon May 28 00:00:00 PDT 2007

Chronic.parse('6/4/2012', :endian_precedence => :little)
  #=> Fri Apr 06 00:00:00 PDT 2012

Chronic.parse('INVALID DATE')
  #=> nil

If the parser can find a date or time, either a Time or Chronic::Span will be returned (depending on the value of :guess). If no date or time can be found, nil will be returned.

See Chronic.parse for detailed usage instructions.

Examples

Chronic can parse a huge variety of date and time formats. Following is a small sample of strings that will be properly parsed. Parsing is case insensitive and will handle common abbreviations and misspellings.

Simple

thursday
november
summer
friday 13:00
mon 2:35
4pm
10 to 8
10 past 2
half past 2
6 in the morning
friday 1pm
sat 7 in the evening
yesterday
today
tomorrow
last week
next week
this tuesday
next month
last winter
this morning
last night
this second
yesterday at 4:00
last friday at 20:00
last week tuesday
tomorrow at 6:45pm
afternoon yesterday
thursday last week

Complex

3 years ago
a year ago
5 months before now
7 hours ago
7 days from now
1 week hence
in 3 hours
1 year ago tomorrow
3 months ago saturday at 5:00 pm
7 hours before tomorrow at noon
3rd wednesday in november
3rd month next year
3rd thursday this september
4th day last week
fourteenth of june 2010 at eleven o'clock in the evening
may seventh '97 at three in the morning

Specific Dates

January 5
22nd of june
5th may 2017
February twenty first
dec 25
may 27th
October 2006
oct 06
jan 3 2010
february 14, 2004
february 14th, 2004
3 jan 2000
17 april 85
5/27/1979
27/5/1979
05/06
1979-05-27
Friday
5
4:00
17:00
0800

Specific Times (many of the above with an added time)

January 5 at 7pm
22nd of june at 8am
1979-05-27 05:00:00
03/01/2012 07:25:09.234567
etc

Time Zones

Chronic allows you to set which Time class to use when constructing times. By default, the built in Ruby time class creates times in your system's local time zone. You can set this to something like ActiveSupport's TimeZone class to get full time zone support.

>> Time.zone = "UTC"
>> Chronic.time_class = Time.zone
>> Chronic.parse("June 15 2006 at 5:45 AM")
=> Thu, 15 Jun 2006 05:45:00 UTC +00:00

Limitations

Chronic uses Ruby's built in Time class for all time storage and computation. Because of this, only times that the Time class can handle will be properly parsed. Parsing for times outside of this range will simply return nil. Support for a wider range of times is planned for a future release.

Contribute

If you'd like to hack on Chronic, start by forking the repo on GitHub:

https://github.com/mojombo/chronic

The best way to get your changes merged back into core is as follows:

Clone down your fork
Create a thoughtfully named topic branch to contain your change
Hack away
Add tests and make sure everything still passes by running rake
Ensure your tests pass in multiple timezones. ie TZ=utc rake TZ=BST rake
If you are adding new functionality, document it in the README
Do not change the version number, we will do that on our end
If necessary, rebase your commits into logical chunks, without errors
Push the branch up to GitHub
Send a pull request for your branch