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for the first week of a year whenever the first Thursday of that year is 7 Jan, for instance 2016. git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@40239 72102866-910b-0410-8b05-ffd578937521
99 lines
2.6 KiB
Objective-C
99 lines
2.6 KiB
Objective-C
/* Implementation of extension methods to base additions
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Copyright (C) 2010 Free Software Foundation, Inc.
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Written by: Richard Frith-Macdonald <rfm@gnu.org>
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This file is part of the GNUstep Base Library.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free
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Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02111 USA.
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*/
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#import "common.h"
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#import "Foundation/NSAutoreleasePool.h"
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#import "GNUstepBase/NSCalendarDate+GNUstepBase.h"
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/**
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* Extension methods for the NSCalendarDate class
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*/
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@implementation NSCalendarDate (GNUstepBase)
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- (NSUInteger) isoYear
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{
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NSUInteger year = [self yearOfCommonEra];
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NSUInteger week = [self weekOfYear];
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NSUInteger month = [self monthOfYear];
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if (week == 1 && month == 12)
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{
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year++;
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}
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else if (week >= 52 && month == 1)
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{
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year--;
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}
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return year;
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}
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- (NSInteger) weekOfYear
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{
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NSInteger dayOfWeek = [self dayOfWeek];
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NSInteger dayOfYear;
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/*
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* Whether a week is considered to be in a year or not depends on its
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* thursday ... so find thursday for the receivers week.
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* NB. this may result in a date which is not in the same year as the
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* receiver.
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*/
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if (dayOfWeek != 4)
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{
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NSAutoreleasePool *arp = [NSAutoreleasePool new];
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NSCalendarDate *thursday;
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/*
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* A week starts on monday ... so adjust from 0 to 7 so that a
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* sunday is counted as the last day of the week.
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*/
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if (dayOfWeek == 0)
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{
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dayOfWeek = 7;
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}
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thursday = [self dateByAddingYears: 0
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months: 0
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days: 4 - dayOfWeek
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hours: 0
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minutes: 0
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seconds: 0];
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dayOfYear = [thursday dayOfYear];
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[arp drain];
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}
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else
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{
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dayOfYear = [self dayOfYear];
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}
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/*
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* Round up to a week boundary, so that when we divide by seven we
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* get a result in the range 1 to 53 as mandated by the ISO standard.
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* Note that dayOfYear starts at 1, too, and hence we must be careful
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* to not round up an exact multiple of 7.
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*/
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dayOfYear += (7 - (dayOfYear - 1) % 7);
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return dayOfYear / 7;
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}
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@end
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