"

 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.

"

!

version

    ^ '$Header: /cvs/stx/stx/libbasic/Date.st,v 1.27 1995-11-11 14:28:13 cg Exp $'

!

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).

    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:

"

! !

!Date class methodsFor:'private'!

initNames

    "read the language specific names"

    |resources|

    DayNames := #('monday'

		  'tuesday'

		  'wednesday'

		  'thursday'

		  'friday'

		  'saturday'

		  'sunday').

    DayAbbrevs := #('mon' 

		    'tue' 

		    'wed'

		    'thu' 

		    'fri' 

		    'sat' 

		    'sun').

    MonthNames := #('january'

		    'february'

		    'march'

		    'april'

		    'may'

		    'june'

		    'july'

		    'august'

		    'september'

		    'october'

		    'november'

		    'december').

    MonthAbbrevs := #('jan'

		      'feb'

		      'mar'

		      'apr'

		      'may'

		      'jun'

		      'jul'

		      'aug'

		      'sep'

		      'oct'

		      'nov'

		      'dec').

    "check for case where Resource-classes are absent"

    ResourcePack notNil ifTrue:[

	resources := ResourcePack for:self.

	DayNames := resources array:DayNames.

	DayAbbrevs := resources array:DayAbbrevs.

	MonthNames := resources array:MonthNames.

	MonthAbbrevs := resources array:MonthAbbrevs.

    ].

    EnvironmentChange := false

    "Date initNames"

!

daysInMonthIndex: monthIndex forYear: yearInteger

    "return the number of days in month monthIndex of

     year yearInteger (modified GNU).

     Return 0 for invalid month index.

     This is the internal version of daysInMonth:forYear:"

    |days|

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

    days := #(31 28 31           "Jan Feb Mar"

	      30 31 30           "Apr May Jun"

	      31 31 30           "Jul Aug Sep"

	      31 30 31           "Oct Nov Dec"

	     ) at: monthIndex.

    (monthIndex == 2) ifTrue:[

	(self leapYear:yearInteger) ifTrue:[

	    ^ days + 1

	]

    ].

    ^ days

    "

     Date daysInMonthIndex:2 forYear:1994

     Date daysInMonthIndex:2 forYear:1980

     Date daysInMonthIndex:2 forYear:1981

    "

! !

!Date class methodsFor:'handling language changes'!

initialize

    "check for case where Resource-classes are absent"

    ResourcePack isNil ifTrue:[

	self initNames

    ] ifFalse:[

	Smalltalk addDependent:self.

	EnvironmentChange := true

    ]

!

update:something

    ((something == #Language) or:[something == #LanguageTerritory]) ifTrue:[

	"just remember change for next access"

	EnvironmentChange := true

    ]

! !

!Date class methodsFor:'general queries'!

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'

    "

!

nameOfDay:dayIndex

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

    EnvironmentChange ifTrue:[

	self initNames

    ].

    ^ DayNames at:dayIndex

    "

     Date nameOfDay:4

    "

!

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

    "

!

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'

    "

!

nameOfMonth:monthIndex

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

    EnvironmentChange ifTrue:[

	self initNames

    ].

    ^ MonthNames at:monthIndex

    "

     Date nameOfMonth:11

     Date nameOfMonth:12

     Date nameOfMonth: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

    "

!

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

    "

!

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

    "

!

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

    "

! 

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

    "

!

yearAsDays: yearInteger

    "Returns the number of days since Jan 1, 1901. (GNU)

     to the first Jan of the year, yearInteger.

     For 1901 this is zero, for 1902 its 365.

     Defined for years >= 1901"

    |y "{ Class: SmallInteger }"|

    y := yearInteger - 1900.

    y := y - 1.

    ^ (y * 365)

	+ (y // 4)

	- (y // 100)

	+ ((y + 300) // 400)

    "

     Date yearAsDays:1901 

     Date yearAsDays:1902   

     Date yearAsDays:1903   

     Date yearAsDays:1904    

     Date yearAsDays:1905     

     Date yearAsDays:1994   

     (Date yearAsDays:2001) - (Date yearAsDays:2000)   

    "

!

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

    "

!

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

! !

!Date class methodsFor:'instance creation'!

fromOSTime:osTime

    "return a date, representing the date given by the operatingSystem time.

     This somewhat clumsy implementation hides the OS's date representation

     (i.e. makes this class independent of what the OS starts its time values with).

     Dont use this method, the osTime representation is totally unportable."

    ^ self basicNew fromOSTime:osTime

    "

     Date fromOSTime:#(0 0)      -> on UNIX: this should return 1st Jan 1970

				    thats where Unix time starts

				    On other systems, it may be something different.

     Date fromOSTime:#(86400 0)  -> on UNIX: the day after

    "

!

today

    "return a date, representing today"

    ^ self fromOSTime:OperatingSystem getTimeParts

    "

     Date today

    "

!

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.

     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.