Chronicity
----------

[http://chaitanyagupta.com/lisp/chronicity/]

A natural language date and time parser for Common Lisp.
by Chaitanya Gupta ([email protected])

Inspired by (and copied verbatim from) from Chronic, the natural
language date and time parser for Ruby by Tom Preston-Werner.
[http://chronic.rubyforge.org/]


Download and Installation
-------------------------

Chronicity depends on the following libraries:
  * cl-ppcre [http://weitz.de/cl-ppcre]
  * cl-interpol [http://weitz.de/cl-interpol]
  * local-time [http://common-lisp.net/project/local-time/]
    Works with release 1.0.1 and later only, will break with older
    versions.

Use quicklisp [http://www.quicklisp.org]:
  (ql:quickload :chronicity)

Or download the latest release here:
  http://chaitanyagupta.com/lisp/chronicity/downloads/chronicity-latest.tar.gz

Or get the cutting-edge version from github:
  git clone git://github.com/chaitanyagupta/chronicity.git

Use ASDF to load:
  (asdf:oos 'asdf:load-op :chronicity)

To run the test suite:
  (asdf:oos 'asdf:test-op :chronicity)

Source code for chronicity-test includes lisp-unit
(lisp-unit.lisp). This might be cause problems (or surprises) if your
image already uses a different version of lisp-unit.
[http://www.cs.northwestern.edu/academics/courses/325/readings/lisp-unit.html]


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

Default for :GUESS is :START.

  (chronicity:parse "next month" :guess :middle)
  => @2009-04-16T00:00:00.000000+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


More Examples
-------------
(Of what Chronicity can parse)

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
-----------

Unlike Chronic, Chronicity doesn't support timezones and seasons
yet. Support is planned for future releases.

Internally, LOCAL-TIME:TIMESTAMP objects are used to represent
time. Any limitation which applies to these objects applies to
CHRONICITY:DATETIME objects as well.

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.