Package COM.INFORMATIMAGO.COMMON-LISP.CESARUM.DATE.UTILITY


Internal date utilities.
Defines utilities to process dates.


See also: COM.INFORMATIMAGO.COMMON-LISP.CESARUM.DATE
          COM.INFORMATIMAGO.COMMON-LISP.CESARUM.GREGORIAN-CALENDAR
          COM.INFORMATIMAGO.COMMON-LISP.CESARUM.JULIAN-CALENDAR

License:

    AGPL3
    
    Copyright Pascal J. Bourguignon 2007 - 2012
    
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.
    
    You should have received a copy of the GNU Affero General Public License
    along with this program.
    If not, see <http://www.gnu.org/licenses/>

*day*
variable
Symbolic duration of one day.
Initial value: 1 day
*duration-keywords*
variable
A list of keywords allowed in duration expressions,
in the order they should be printed.
Initial value: (YEAR MONTH WEEK DAY HOUR MINUTE SECONDE)
*hour*
variable
Symbolic duration of one hour.
Initial value: 1 hour
*minute*
variable
Symbolic duration of one minute.
Initial value: 1 minute
*month*
variable
Symbolic duration of one month.
Initial value: 1 month
*quarter*
variable
Symbolic duration of one quarter.
Initial value: 3 months
*seconde*
variable
Symbolic duration of one second.
Initial value: 1 seconde
*week*
variable
Symbolic duration of one week.
Initial value: 1 week
*year*
variable
Symbolic duration of one year.
Initial value: 1 year
+april+
constant
The number of the April month in the Gregorial calendar.
Initial value: 4
+august+
constant
The number of the August month in the Gregorial calendar.
Initial value: 8
+december+
constant
The number of the December month in the Gregorial calendar.
Initial value: 12
+february+
constant
The number of the February month in the Gregorial calendar.
Initial value: 2
+january+
constant
The number of the January month in the Gregorial calendar.
Initial value: 1
+july+
constant
The number of the July month in the Gregorial calendar.
Initial value: 7
+june+
constant
The number of the June month in the Gregorial calendar.
Initial value: 6
+march+
constant
The number of the Marchmonth in the Gregorial calendar.
Initial value: 3
+may+
constant
The number of the May month in the Gregorial calendar.
Initial value: 5
+november+
constant
The number of the November month in the Gregorial calendar.
Initial value: 11
+october+
constant
The number of the October month in the Gregorial calendar.
Initial value: 10
+september+
constant
The number of the September month in the Gregorial calendar.
Initial value: 9
(as-list-of-numbers date)
generic-function
Return the values of the date from the most significant
number to the last. It can be a list of a single number.
This is meaningful only in the context of the given date class, and used
to compare two dates of the same class.
(collapse-julian-duration duration)
generic-function
DO:     Collapse weeks as 7 days.
RETURN: secondes; minutes; hours; days; months; years
NOTE:   If you add keywords to *DURATION-KEYWORDS* you may have to
        override this method. 
(compare-lists-of-numbers a b)
function
PRE:    (and (proper-list-p a)
             (proper-list-p b)
             (every (function realp) a)
             (every (function realp) b))
RETURN: The lexicographical order of the two lists of numbers.
(current-timezone)
function
RETURN:  The current default timezone, expressed as a number of seconds
         from Greenwich; East positive.
WARNING: COMMON-LISP convention is West positive.
(date-after date duration)
generic-function
RETURN: The date DURATION after DATE.
(date-before date duration)
generic-function
RETURN: The date DURATION before DATE.
(date/= date1 date2)
generic-function
RETURN: Whether DATE1 is different from DATE2.
(date< date1 date2)
generic-function
RETURN: Whether DATE1 is before DATE2.
(date<= date1 date2)
generic-function
RETURN: Whether DATE1 is before or the same as DATE2.
(date= date1 date2)
generic-function
RETURN: Whether DATE1 is the same as DATE2.
(date> date1 date2)
generic-function
RETURN: Whether DATE1 is after DATE2.
(date>= date1 date2)
generic-function
RETURN: Whether DATE1 is after or the same as DATE2.
(day duration)
generic-function
RETURN: The day of the duration.
NOTE:   This is not the duration expressed in day, just the day
        component of the duration.
(define-date-compare-methods class)
macro
DO:     Define date comparison methods.
(dst-in-year year)
function
RETURN: A list of (year m d) where DST is shifted in or out in the YEAR/
BUG:    This uses the undetermined  local timezone, we don't know
        what country DST is returned...
duration
class
We store durations 'symbolically'. The 'units' may be colinear in a
given calendar, but we don't collapse them because either they may
be not colinear in other calendars, or their ratio may not be
always the same (eg. 1 year is 24 months in the Davian calendar vs
12 months in the Gregorian calendar, or 1 month may be 28, 29, 30
or 31 days).

There is no order for durations.

Moreover, the set of units is not hardwired, the client may add new
units to the *DURATION-KEYWORDS* list.  Only the units listed in
*DURATION-KEYWORDS* are processed by the DURATION arithmetic operators.

This allows us to use these DURATION objects with respect to any
calendar.
Class precedence list: DURATION STANDARD-OBJECT T
(duration &rest expression &key &allow-other-keys)
function
RETURN:  A new DURATION instance, initialized with the EXPRESSION.
NOTE:    Only the keywords listed in *DURATION-KEYWORDS* are really allowed.
(duration* a n)
generic-function
RETURN: The product of a duration by a number.
(duration+ a b)
generic-function
RETURN: The sum of two durations.
(duration- a b)
generic-function
RETURN: The difference of two durations.
(duration-between end start)
generic-function
Return the DURATION between END and START.
Both END and START dates must be of the same class.
(english-name-of-julian-month month)
function
RETURN: A string containing the name in English of the MONTH
        (Julian, Gregorian, etc, calendars).
(english-name-of-julian-weekday weekday)
function
RETURN: A string containing the name in English of the WEEKDAY.
(hms60-from-secondes secondes)
function
RETURN: seconde ; minute ; hour
POST:   (or (not (integerp secondes))
            (= secondes (multiple-value-call (function hms-to-secondes)
                                             (hms60-from-secondes secondes))))
(hms60-to-secondes seconde minute hour)
function
RETURN: The number of seconds corresponding to hour:minute:second in base sixty.
(hour duration)
generic-function
RETURN: The hour of the duration.
NOTE:   This is not the duration expressed in hour, just the hour
        component of the duration.
(julian-date seconde minute hour julian-day-number)
function
RETURN: The Julian Date for the given time and Julian Day Number.
URL:    <http://en.wikipedia.org/wiki/Julian_day#Calculation>
(julian-day-number/gregorian day month year)
function
RETURN: The Julian Day Number for the given Gregorian Date.
URL:    <http://en.wikipedia.org/wiki/Julian_day#Calculation>
(julian-day-number/julian day month year)
function
RETURN: The Julian Day Number for the given Julian Date.
URL:    <http://en.wikipedia.org/wiki/Julian_day#Calculation>
(minute duration)
generic-function
RETURN: The minute of the duration.
NOTE:   This is not the duration expressed in minute, just the minute
        component of the duration.
(month duration)
generic-function
RETURN: The month of the duration.
NOTE:   This is not the duration expressed in month, just the month
        component of the duration.
(seconde duration)
generic-function
RETURN: The seconde of the duration.
NOTE:   This is not the duration expressed in seconde, just the seconde
        component of the duration.
(week duration)
generic-function
RETURN: The week of the duration.
NOTE:   This is not the duration expressed in week, just the week
        component of the duration.
(weekday-of-julian-date julian-date)
function
RETURN: The Day of the week of the given Julian Day.
        0 = Monday, 1 = Tuesday, ..., 6 = Sunday.
URL:    <http://en.wikipedia.org/wiki/Julian_day#Calculation>
(year duration)
generic-function
RETURN: The year of the duration.
NOTE:   This is not the duration expressed in year, just the year
        component of the duration.