gdate.h

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 /*
  21  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  22  * file for a list of people on the GLib Team.  See the ChangeLog
  23  * files for a list of changes.  These files are distributed with
  24  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  25  */
  26
  27 #ifndef __G_DATE_H__
  28 #define __G_DATE_H__
  29
  30 #include <gquark.h>
  31
  32 G_BEGIN_DECLS
  33
  34 /* GDate
  35  *
  36  * Date calculations (not time for now, to be resolved). These are a
  37  * mutant combination of Steffen Beyer's DateCalc routines
  38  * (http://www.perl.com/CPAN/authors/id/STBEY/) and Jon Trowbridge's
  39  * date routines (written for in-house software).  Written by Havoc
  40  * Pennington <hp@pobox.com>
  41  */
  42
  43 typedef gint32  GTime;
  44 typedef guint16 GDateYear;
  45 typedef guint8  GDateDay;   /* day of the month */
  46 typedef struct _GDate GDate;
  47 /* make struct tm known without having to include time.h */
  48 struct tm;
  49
  50 /* enum used to specify order of appearance in parsed date strings */
  51 typedef enum
  52 {
  53   G_DATE_DAY   = 0,
  54   G_DATE_MONTH = 1,
  55   G_DATE_YEAR  = 2
  56 } GDateDMY;
  57
  58 /* actual week and month values */
  59 typedef enum
  60 {
  61   G_DATE_BAD_WEEKDAY  = 0,
  62   G_DATE_MONDAY       = 1,
  63   G_DATE_TUESDAY      = 2,
  64   G_DATE_WEDNESDAY    = 3,
  65   G_DATE_THURSDAY     = 4,
  66   G_DATE_FRIDAY       = 5,
  67   G_DATE_SATURDAY     = 6,
  68   G_DATE_SUNDAY       = 7
  69 } GDateWeekday;
  70 typedef enum
  71 {
  72   G_DATE_BAD_MONTH = 0,
  73   G_DATE_JANUARY   = 1,
  74   G_DATE_FEBRUARY  = 2,
  75   G_DATE_MARCH     = 3,
  76   G_DATE_APRIL     = 4,
  77   G_DATE_MAY       = 5,
  78   G_DATE_JUNE      = 6,
  79   G_DATE_JULY      = 7,
  80   G_DATE_AUGUST    = 8,
  81   G_DATE_SEPTEMBER = 9,
  82   G_DATE_OCTOBER   = 10,
  83   G_DATE_NOVEMBER  = 11,
  84   G_DATE_DECEMBER  = 12
  85 } GDateMonth;
  86
  87 #define G_DATE_BAD_JULIAN 0U
  88 #define G_DATE_BAD_DAY    0U
  89 #define G_DATE_BAD_YEAR   0U
  90
  91 /* Note: directly manipulating structs is generally a bad idea, but
  92  * in this case it's an *incredibly* bad idea, because all or part
  93  * of this struct can be invalid at any given time. Use the functions,
  94  * or you will get hosed, I promise.
  95  */
  96 struct _GDate
  97 {
  98   guint julian_days : 32; /* julian days representation - we use a
  99                            *  bitfield hoping that 64 bit platforms
 100                            *  will pack this whole struct in one big
 101                            *  int
 102                            */
 103
 104   guint julian : 1;    /* julian is valid */
 105   guint dmy    : 1;    /* dmy is valid */
 106
 107   /* DMY representation */
 108   guint day    : 6;
 109   guint month  : 4;
 110   guint year   : 16;
 111 };
 112
 113 /* g_date_new() returns an invalid date, you then have to _set() stuff
 114  * to get a usable object. You can also allocate a GDate statically,
 115  * then call g_date_clear() to initialize.
 116  */
 117 GDate*       g_date_new                   (void);
 118 GDate*       g_date_new_dmy               (GDateDay     day,
 119                                            GDateMonth   month,
 120                                            GDateYear    year);
 121 GDate*       g_date_new_julian            (guint32      julian_day);
 122 void         g_date_free                  (GDate       *date);
 123
 124 /* check g_date_valid() after doing an operation that might fail, like
 125  * _parse.  Almost all g_date operations are undefined on invalid
 126  * dates (the exceptions are the mutators, since you need those to
 127  * return to validity).
 128  */
 129 gboolean     g_date_valid                 (GDate       *date);
 130 gboolean     g_date_valid_day             (GDateDay     day) G_GNUC_CONST;
 131 gboolean     g_date_valid_month           (GDateMonth month) G_GNUC_CONST;
 132 gboolean     g_date_valid_year            (GDateYear  year) G_GNUC_CONST;
 133 gboolean     g_date_valid_weekday         (GDateWeekday weekday) G_GNUC_CONST;
 134 gboolean     g_date_valid_julian          (guint32 julian_date) G_GNUC_CONST;
 135 gboolean     g_date_valid_dmy             (GDateDay     day,
 136                                            GDateMonth   month,
 137                                            GDateYear    year) G_GNUC_CONST;
 138
 139 GDateWeekday g_date_weekday               (GDate       *date);
 140 GDateMonth   g_date_month                 (GDate       *date);
 141 GDateYear    g_date_year                  (GDate       *date);
 142 GDateDay     g_date_day                   (GDate       *date);
 143 guint32      g_date_julian                (GDate       *date);
 144 guint        g_date_day_of_year           (GDate       *date);
 145 /* First monday/sunday is the start of week 1; if we haven't reached
 146  * that day, return 0. These are not ISO weeks of the year; that
 147  * routine needs to be added.
 148  * these functions return the number of weeks, starting on the
 149  * corrsponding day
 150  */
 151 guint        g_date_monday_week_of_year   (GDate      *date);
 152 guint        g_date_sunday_week_of_year   (GDate      *date);
 153
 154 /* If you create a static date struct you need to clear it to get it
 155  * in a sane state before use. You can clear a whole array at
 156  * once with the ndates argument.
 157  */
 158 void         g_date_clear                 (GDate       *date,
 159                                            guint        n_dates);
 160
 161 /* The parse routine is meant for dates typed in by a user, so it
 162  * permits many formats but tries to catch common typos. If your data
 163  * needs to be strictly validated, it is not an appropriate function.
 164  */
 165 void         g_date_set_parse             (GDate       *date,
 166                                            const gchar *str);
 167 void         g_date_set_time              (GDate       *date,
 168                                            GTime        time);
 169 void         g_date_set_month             (GDate       *date,
 170                                            GDateMonth   month);
 171 void         g_date_set_day               (GDate       *date,
 172                                            GDateDay     day);
 173 void         g_date_set_year              (GDate       *date,
 174                                            GDateYear    year);
 175 void         g_date_set_dmy               (GDate       *date,
 176                                            GDateDay     day,
 177                                            GDateMonth   month,
 178                                            GDateYear    y);
 179 void         g_date_set_julian            (GDate       *date,
 180                                            guint32      julian_date);
 181 gboolean     g_date_is_first_of_month     (GDate       *date);
 182 gboolean     g_date_is_last_of_month      (GDate       *date);
 183
 184 /* To go forward by some number of weeks just go forward weeks*7 days */
 185 void         g_date_add_days              (GDate       *date,
 186                                            guint        n_days);
 187 void         g_date_subtract_days         (GDate       *date,
 188                                            guint        n_days);
 189
 190 /* If you add/sub months while day > 28, the day might change */
 191 void         g_date_add_months            (GDate       *date,
 192                                            guint        n_months);
 193 void         g_date_subtract_months       (GDate       *date,
 194                                            guint        n_months);
 195
 196 /* If it's feb 29, changing years can move you to the 28th */
 197 void         g_date_add_years             (GDate       *date,
 198                                            guint        n_years);
 199 void         g_date_subtract_years        (GDate       *date,
 200                                            guint        n_years);
 201 gboolean     g_date_is_leap_year          (GDateYear    year) G_GNUC_CONST;
 202 guint8       g_date_days_in_month         (GDateMonth   month,
 203                                            GDateYear    year) G_GNUC_CONST;
 204 guint8       g_date_monday_weeks_in_year  (GDateYear    year) G_GNUC_CONST;
 205 guint8       g_date_sunday_weeks_in_year  (GDateYear    year) G_GNUC_CONST;
 206
 207 /* qsort-friendly (with a cast...) */
 208 gint         g_date_compare               (GDate       *lhs,
 209                                            GDate       *rhs);
 210 void         g_date_to_struct_tm          (GDate       *date,
 211                                            struct tm   *tm);
 212
 213 /* Just like strftime() except you can only use date-related formats.
 214  *   Using a time format is undefined.
 215  */
 216 gsize        g_date_strftime              (gchar       *s,
 217                                            gsize        slen,
 218                                            const gchar *format,
 219                                            GDate       *date);
 220
 221 G_END_DECLS
 222
 223 #endif /* __G_DATE_H__ */
 224