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Chronicity

A natural language date and time parser for Common Lisp.

Inspired by (and copied verbatim from) from Chronic, the natural language date and time parser for Ruby by Tom Preston-Werner.

To understand how Chronicity works, read this post: Writing a natural language date and time parser

Download and Installation

Use quicklisp:

(ql:quickload "chronicity")

Or get the cutting-edge version from github: https://github.com/chaitanyagupta/chronicity/tree/master

Or get the latest stable release (usually updates before quicklisp): https://github.com/chaitanyagupta/chronicity/releases

Usage

Use CHRONICITY:PARSE to parse date/time strings.

If *NOW* is not set, "now" is assumed to be this instant. All relative date/time calculations are made with respect to *NOW*.

(setf chronicity:*now* (chronicity:make-datetime 2009 3 27 12 34 56))
=> @2009-03-27T12:34:56.000000+05:30

(chronicity:parse "today")
=> @2009-03-27T13:00:00.000000+05:30

(chronicity:parse "tomorrow" :now (chronicity:make-date 2009 1 1))
=> @2009-01-02T00:00:00.000000+05:30

(chronicity:parse "3 days from now")
=> @2009-03-30T12:34:56.000000+05:30

(chronicity:parse "next month")
=> @2009-04-01T00:00:00.000000+05:30

:ENDIAN-PREFERENCE indicates which date format to prefer in case of ambiguity over days and months. :LITTLE indicates the format "dd/mm/yyyy", :MIDDLE indicates "mm/dd/yyy". Default is :LITTLE.

(chronicity:parse "1/2/2003")
=> @2003-02-01T00:00:00.000000+05:30

(chronicity:parse "1/2/2003" :endian-preference :middle)
=> @2003-01-02T00:00:00.000000+05:30

Default value for :CONTEXT is :FUTURE.

(chronicity:parse "April 1st at 12:30 PM")
=> @2009-04-01T12:30:00.000000+05:30

(chronicity:parse "April 1st at 12:30 PM" :context :past)
=> @2008-04-01T12:30:00.000000+05:30

CHRONICITY:PARSE usually returns a DATETIME object. Its attributes can be accessed using the datetime readers.

(chronicity:parse "next month" :guess :end)
=> @2009-04-30T23:59:59.000000+05:30

(values (chronicity:year-of *)
        (chronicity:month-of *)
        (chronicity:day-of *)
        (chronicity:hour-of *)
        (chronicity:minute-of *)
        (chronicity:sec-of *))
=> 2009, 4, 30, 23, 59, 59

Passing NIL as the value for :GUESS returns a SPAN, which is a range of datetime values.

(chronicity:parse "next month" :guess nil)
=> #<CHRONICITY::SPAN 2009-04-01T00:00:00.000000+05:30...2009-05-01T00:00:00.000000+05:30>

(values (chronicity:span-start *)
        (chronicity:span-end *)
        (chronicity:span-end-included-p *))
=> @2009-04-01T00:00:00.000000+05:30,
   @2009-05-01T00:00:00.000000+05:30,
   NIL

Other possible values are :START, :MIDDLE, or :END which return the start, mid-point or the end of a span respectively.

Input Examples

Simple

thursday
november
summer
friday 13:00
mon 2:35
4pm
6 in the morning
friday 1pm
sat 7 in the evening
yesterday
today
tomorrow
this tuesday
next month
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
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

Specific Dates

January 5
dec 25
may 27th
October 2006
oct 06
jan 3 2010
february 14, 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
1979-05-27 05:00:00
etc

Limitations

Chronicity only works with the current timezone (as returned by LOCAL-TIME:*DEFAULT-TIMEZONE*) . Support for different timezones is planned for a future release.

The datetime object(s) returned by the parser are of type LOCAL-TIME:TIMESTAMP. Be aware of any limitations that may apply to them.

Another problem is that parsing ordinals as words is supported except for second, which is ambiguous with second the unit of time. This should be fixed in a future release.