"

 COPYRIGHT (c) 1989 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

Magnitude subclass:#Date

	instanceVariableNames:'dateEncoding'

	classVariableNames:'DayNames MonthNames DayAbbrevs MonthAbbrevs EnvironmentChange'

	poolDictionaries:''

	category:'Magnitude-General'

!

!Date class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1989 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

documentation

"

    Instances of Date represent dates as year, month and day encoded in the 

    (private & hidden) instance dateEncoding. The value found there is 

    year*100*100 + month*100 + day (which makes magnitude-like comparison of 

    dates easy, but is not guaranteed for future versions).

    Do not depend on the internal representation.

    The old representation used days since 1st Jan. 1901 internally - 

    with the new implementation, it is possible to reasonably represent almost 

    any Date.  (which insurance companies will like, since they can now 

    represent even very old peoples birthday :-)

    Notice: no correction for pre-Julian dates is done.

    The printed representation of dates is controlled by resource definitions -

    thus national variants are already supported (see file 'resources/Date.rs').

    Compatibility notice:

        due to some historic reasons, there are some methods found twice

        with different names in this class. The old ST/X methods will vanish in

        one of the next releases, and kept for a while to support existing

        applications (the info on how these methods should be named came 

        somewhat late from the testers ..).

        Please do not use methods marked as obsolete in their comment.

    Most useful methods:

        Date today

        (Date today) addDays:

        (Date today) subtractDays:

    [author:]

        Claus Gittinger

    [see also:]

        Time AbstractTime

        Filename

        OperatingSystem

"

! !

!Date class methodsFor:'instance creation'!

fromDays:dayCount

    "return a new Date, given the day-number starting with 0 at 1.Jan 1901;

     (i.e. 'Date fromDays:0' returns 1st Jan. 1901).

     Date asDays is the reverse operation.

     Added for GNU/ST-80 compatibility"

    |yr rest d|

    "approx. year"

    yr := (dayCount // 366) + 1901.

    rest := dayCount - (self yearAsDays:yr) + 1. "+1 for ST-80 compatibility"

    d := self daysInYear:yr.

    (rest > d) ifTrue:[

        "adjust"

        yr := yr + 1.

        rest := rest - d.

    ].

    ^ self newDay:rest year:yr

    "

     Date fromDays:0     -> 1 jan 1901

     Date fromDays:365   -> 1 jan 1902

     Date fromDays:730   -> 1 jan 1903

     Date fromDays:1095  -> 1 jan 1903

     Date fromDays:1460  ->31 dec 1904 since 1904 was a leap year

    "

    "Modified: 1.7.1996 / 14:24:25 / cg"

!

newDay:day month:month year:year

    "return a new Date, given the day, month and year.

     For your convenience, month may be either an integer 

     or the months name as a string. 

     Year may be the actual year (such as 1890, 2001) or the number 

     of years since 1900 (which is rubbish ST-80 compatibility: 

     it will be totally useless in a few years ...).

     You better not use this short-year feature in your programs."

    |monthIndex ok yr|

    yr := year.

    yr < 100 ifTrue:[

        yr := yr + 1900.

    ].

    month isInteger ifTrue:[

        monthIndex := month

    ] ifFalse:[

        monthIndex := self indexOfMonth:month

    ].

    (monthIndex == 2 and:[day == 29]) ifTrue:[

        ok := self leapYear:yr

    ] ifFalse:[

        ok := day <= (self daysInMonth:month forYear:yr)

    ].

    ((day > 0) and:[ok]) ifTrue:[

        ^ self basicNew dateEncoding:(((yr * 100) + monthIndex) * 100) + day

    ].

    "this error is triggered if you try to create a date from an

     invalid year/month/day combination;

     Such as 29-feb-year, where year is no leap year

    "

    self error:'invalid date'

    "

     Date newDay:8  month:'may' year:1993

     Date newDay:8  month:5     year:1994

     Date newDay:29 month:'feb' year:1994

     Date newDay:29 month:'feb' year:1993

     Date newDay:28 month:'feb' year:5

     Date newDay:28 month:'feb' year:95

    "

    "Modified: 19.4.1996 / 15:28:15 / cg"

!

newDay:dayInYear year:year

    "return a new Date, given the year and the day-in-year (starting at 1).

     See also: Date today / Time now / AbsoluteTime now.

     ST-80 compatibility"

    |monthAndDay|

    (dayInYear between:1 and:365) ifFalse:[

        ((dayInYear == 366) and:[self leapYear:year]) ifFalse:[

            "

             this error is triggered, when you try to create a

             day from an invalid day-in-year; 

             for example, 366 in a non-leap year.

             I dont know, if ST-80 wraps to the next year(s) in this case.

            "

            ^ self error:'invalid date'

        ]

    ].

    monthAndDay := self monthAndDayFromDayInYear:dayInYear forYear:year.

    ^ self newDay:(monthAndDay at:2) month:(monthAndDay at:1) year:year

    "

     Date newDay:150 year:1994

     Date newDay:1 year:1994

     Date newDay:1 year:1901

     Date newDay:1 year:1902

     Date newDay:365 year:1992

     Date newDay:366 year:1992

     Date newDay:365 year:1994

     Date newDay:366 year:1994

    "

    "Modified: 1.7.1996 / 14:22:24 / cg"

!

readFrom:aStringOrStream onError:exceptionBlock

    "return a new Date, reading a printed representation from aStream.

     Notice, that this is not the storeString format and 

     is different from the format expected by readFrom:.

     BUG:

       This method assumes american format (i.e. month-day-year) instead

       of the german/french and other day-month-year.

       There ought to be a nationalized variant of this."

    ErrorSignal handle:[:ex |

        ^ exceptionBlock value

    ] do:[

        |str month day year|

        str := aStringOrStream readStream.

        [str peek isLetterOrDigit] whileFalse:[str next].

        (str peek isDigit) ifTrue:[

        ].

        [str peek isLetterOrDigit] whileFalse:[str next].

        (str peek isLetter) ifTrue:[

            month := str nextAlphaNumericWord.

            day isNil ifTrue:[

                [str peek isLetterOrDigit] whileFalse:[str next].

            ]

        ] ifFalse:[

            month := self nameOfMonth:day.

        ].

        [str peek isLetterOrDigit] whileFalse:[str next].

    ].

    "

     Date readFromString:'31 December 1992'  

     Date readFromString:'December, 5, 1992'  

     Date readFromString:'December, 5 1992'  

     Date readFromString:'3-jan-95'           

     Date readFromString:'12/31/1992'        

     Date readFromString:'15.4.1992'         -> german; leads to an error

     Date readFromString:'10.4.1992'         -> german; leads to a wrong date

     Date readFromString:'10.4.1992' onError:['wrong date']

    "

    "Created: 16.11.1995 / 22:50:17 / cg"

    "Modified: 8.10.1996 / 19:25:39 / cg"

!

today

    "return a date, representing today.

     See also: Time now / AbsoluteTime now."

    ^ self fromOSTime:(OperatingSystem getOSTime)

    "

     Date today

    "

    "Modified: 1.7.1996 / 15:20:16 / cg"

! !

!Date class methodsFor:'general queries'!

abbreviatedNameOfDay:dayIndex

    "given a day index (1..7), return the abbreviated name

     of the day"

    EnvironmentChange ifTrue:[

	self initNames

    ].

    ^ DayAbbrevs at:dayIndex

    "

     Date abbreviatedNameOfDay:4

    "

!

abbreviatedNameOfMonth:monthIndex

    "given a month index (1..12), return the abbreviated name

     of the month"

    EnvironmentChange ifTrue:[

	self initNames

    ].

    ^ MonthAbbrevs at:monthIndex

    "

     Date abbreviatedNameOfMonth:11

     Date abbreviatedNameOfMonth:12

    "

!

dateAndTimeNow

    "return an array containing the date and time of now"

    ^ Time dateAndTimeNow

    "

     Date dateAndTimeNow

    "

!

dayOfWeek:dayName

    "given the name of a day (either string or symbol),

     return the day-index (1 for monday; 7 for sunday).

     Return 0 for invalid day name"

    EnvironmentChange ifTrue:[

	self initNames

    ].

    ^ DayNames indexOf:dayName

    "

     Date dayOfWeek:'wednesday'

    "

!

daysInMonth:month forYear:yearInteger

    "given the name of a month and a year, return the number 

     of days this month has (modified GNU).

     return 0 if the month name was invalid.

     For your convenience, month maybe an integer or name-string."

    |monthIndex "{ Class: SmallInteger }"|

    month isInteger ifTrue:[

	monthIndex := month

    ] ifFalse:[

	monthIndex := self indexOfMonth:month

    ].

    ^ self daysInMonthIndex:monthIndex forYear:yearInteger

    "

     Date daysInMonth:2 forYear:1980

     Date daysInMonth:2 forYear:1981

     Date daysInMonth:'feb' forYear:1981

    "

!

daysInYear:yearInteger

    "return the number of days in a year"

    (self leapYear:yearInteger) ifTrue:[^ 366].

    ^ 365

    "

     Date daysInYear:1900  

     Date daysInYear:1901 

     Date daysInYear:1904 

     Date daysInYear:1980 

     Date daysInYear:1981

    "

!

daysUntilMonth:month forYear:yearInteger

    "given the name of a month and a year, return the number 

     of days from 1st january to last of prev month of that year.

     Return 0 if the month name/index is invalid or is january.

     For your convenience, month maybe an integer or name-string."

    |monthIndex "{ Class: SmallInteger }"

     sumDays    "{ Class: SmallInteger }" |

    month isInteger ifTrue:[

	monthIndex := month

    ] ifFalse:[

	monthIndex := self indexOfMonth:month

    ].

    (monthIndex between:1 and:12) ifFalse:[^ 0].

    sumDays := 0.

    1 to:monthIndex-1 do:[:m |

	sumDays := sumDays + (self daysInMonthIndex:m forYear:yearInteger)

    ].

    ^ sumDays

    "

     Date daysUntilMonth:'feb' forYear:1993

     Date daysUntilMonth:'jan' forYear:1993

    "

!

indexOfMonth:aMonthString

    "given the name of a month (either string or symbol),

     return the month-index (1 for jan; 12 for december).

     The given string may be a full or abbreviated name,

     case is ignored.

     Return 0 for invalid month name."

    |idx name|

    EnvironmentChange ifTrue:[

	self initNames

    ].

    name := aMonthString asLowercase.

    idx := MonthAbbrevs indexOf:name.

    idx ~~ 0 ifTrue:[^ idx].

    idx := MonthNames indexOf:name.

    idx ~~ 0 ifTrue:[^ idx].

    name at:1 put:(name at:1) asUppercase.

    idx := MonthAbbrevs indexOf:name.

    idx ~~ 0 ifTrue:[^ idx].

    idx := MonthNames indexOf:name.

    idx ~~ 0 ifTrue:[^ idx].

    ^ idx

    "

     Date indexOfMonth:'jan'

     Date indexOfMonth:'Jan'

     Date indexOfMonth:'December'

    "

!

isLeapYear:yearInteger

    "Return true, if a year is a leap year.

     Obsolete:

	 Please use the ST-80 compatible #leapYear for new programs, 

	 since this method will vanish."

    ^ self leapYear:yearInteger

!

leapYear:yearInteger

    "return true, if yearInteger is a leap year."

    |y "{ Class: SmallInteger }"|

    y := yearInteger.

    (y \\ 4 == 0) ifTrue:[

	(y \\ 100 ~~ 0) ifTrue:[^ true].

	(y \\ 400 == 0) ifTrue:[^ true]

    ].

    ^ false

    "

     Date leapYear:1992

     Date leapYear:1994

     Date leapYear:1900

     Date leapYear:2000

    "

!

monthAndDayFromDayInYear:aDayInYear forYear:yearInteger

    "given a day-in-year (1..365) return an Array containing the

     month index and the day-in-month. Return nil if the argument is invalid."

    |restDays daysInMonth|

    restDays := aDayInYear.

    restDays < 1 ifTrue:[^ nil].

    1 to:12 do:[:m |

	daysInMonth := self daysInMonthIndex:m forYear:yearInteger.

	restDays <= daysInMonth ifTrue:[

	    ^ Array with:m with:restDays

	].

	restDays := restDays - daysInMonth 

    ].

    restDays > daysInMonth ifTrue:[^ nil].

    ^ Array with:12 with:restDays

    "

     Date monthAndDayFromDayInYear:66 forYear:1980

     Date monthAndDayFromDayInYear:66 forYear:1981

    "

!

nameOfDay:dayIndex

    "given a day index (1..7), return the name of the day" 

    EnvironmentChange ifTrue:[

	self initNames

    ].

    ^ DayNames at:dayIndex

    "

     Date nameOfDay:4

    "

!

nameOfMonth:monthIndex

    "given a month index (1..12), return the name of the month"