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glib/gdate.c
CST 1999 Shawn T. Amundson b9ef2b41db inserted additional note to look for ChangeLog and AUTHORS file for a log 
Wed Feb 24 00:08:42 CST 1999 Shawn T. Amundson <amundson@gtk.org>

        * *.[ch]: inserted additional note to look for ChangeLog and
	  AUTHORS file for a log of modifications.
1999-02-24 06:14:27 +00:00

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/* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* Modified by the GLib Team and others 1997-1999. See the AUTHORS
* file for a list of people on the GLib Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GLib at ftp://ftp.gtk.org/pub/gtk/.
*/
/*
* MT safe
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "glib.h"
#include <time.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <locale.h>
GDate*
g_date_new ()
{
GDate *d = g_new0 (GDate, 1); /* happily, 0 is the invalid flag for everything. */
return d;
}
GDate*
g_date_new_dmy (GDateDay day, GDateMonth m, GDateYear y)
{
GDate *d;
g_return_val_if_fail (g_date_valid_dmy (day, m, y), NULL);
d = g_new (GDate, 1);
d->julian = FALSE;
d->dmy = TRUE;
d->month = m;
d->day = day;
d->year = y;
g_assert (g_date_valid (d));
return d;
}
GDate*
g_date_new_julian (guint32 j)
{
GDate *d;
g_return_val_if_fail (g_date_valid_julian (j), NULL);
d = g_new (GDate, 1);
d->julian = TRUE;
d->dmy = FALSE;
d->julian_days = j;
g_assert (g_date_valid (d));
return d;
}
void
g_date_free (GDate *d)
{
g_return_if_fail (d != NULL);
g_free (d);
}
gboolean
g_date_valid (GDate *d)
{
g_return_val_if_fail (d != NULL, FALSE);
return (d->julian || d->dmy);
}
static const guint8 days_in_months[2][13] =
{ /* error, jan feb mar apr may jun jul aug sep oct nov dec */
{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
{ 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } /* leap year */
};
static const guint16 days_in_year[2][14] =
{ /* 0, jan feb mar apr may jun jul aug sep oct nov dec */
{ 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
{ 0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
gboolean
g_date_valid_month (GDateMonth m)
{
return ( (m > G_DATE_BAD_MONTH) && (m < 13) );
}
gboolean
g_date_valid_year (GDateYear y)
{
return ( y > G_DATE_BAD_YEAR );
}
gboolean
g_date_valid_day (GDateDay d)
{
return ( (d > G_DATE_BAD_DAY) && (d < 32) );
}
gboolean
g_date_valid_weekday (GDateWeekday w)
{
return ( (w > G_DATE_BAD_WEEKDAY) && (w < 8) );
}
gboolean
g_date_valid_julian (guint32 j)
{
return (j > G_DATE_BAD_JULIAN);
}
gboolean
g_date_valid_dmy (GDateDay d,
GDateMonth m,
GDateYear y)
{
return ( (m > G_DATE_BAD_MONTH) &&
(m < 13) &&
(d > G_DATE_BAD_DAY) &&
(y > G_DATE_BAD_YEAR) && /* must check before using g_date_is_leap_year */
(d <= (g_date_is_leap_year (y) ?
days_in_months[1][m] : days_in_months[0][m])) );
}
/* "Julian days" just means an absolute number of days, where Day 1 ==
* Jan 1, Year 1
*/
static void
g_date_update_julian (GDate *d)
{
GDateYear year;
gint index;
g_return_if_fail (d != NULL);
g_return_if_fail (d->dmy);
g_return_if_fail (!d->julian);
g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
/* What we actually do is: multiply years * 365 days in the year,
* add the number of years divided by 4, subtract the number of
* years divided by 100 and add the number of years divided by 400,
* which accounts for leap year stuff. Code from Steffen Beyer's
* DateCalc.
*/
year = d->year - 1; /* we know d->year > 0 since it's valid */
d->julian_days = year * 365U;
d->julian_days += (year >>= 2); /* divide by 4 and add */
d->julian_days -= (year /= 25); /* divides original # years by 100 */
d->julian_days += year >> 2; /* divides by 4, which divides original by 400 */
index = g_date_is_leap_year (d->year) ? 1 : 0;
d->julian_days += days_in_year[index][d->month] + d->day;
g_return_if_fail (g_date_valid_julian (d->julian_days));
d->julian = TRUE;
}
static void
g_date_update_dmy (GDate *d)
{
GDateYear y;
GDateMonth m;
GDateDay day;
guint32 A, B, C, D, E, M;
g_return_if_fail (d != NULL);
g_return_if_fail (d->julian);
g_return_if_fail (!d->dmy);
g_return_if_fail (g_date_valid_julian (d->julian_days));
/* Formula taken from the Calendar FAQ; the formula was for the
* Julian Period which starts on 1 January 4713 BC, so we add
* 1,721,425 to the number of days before doing the formula.
*
* I'm sure this can be simplified for our 1 January 1 AD period
* start, but I can't figure out how to unpack the formula.
*/
A = d->julian_days + 1721425 + 32045;
B = ( 4 *(A + 36524) )/ 146097 - 1;
C = A - (146097 * B)/4;
D = ( 4 * (C + 365) ) / 1461 - 1;
E = C - ((1461*D) / 4);
M = (5 * (E - 1) + 2)/153;
m = M + 3 - (12*(M/10));
day = E - (153*M + 2)/5;
y = 100 * B + D - 4800 + (M/10);
#ifdef G_ENABLE_DEBUG
if (!g_date_valid_dmy (day, m, y))
{
g_warning ("\nOOPS julian: %u computed dmy: %u %u %u\n",
d->julian_days, day, m, y);
}
#endif
d->month = m;
d->day = day;
d->year = y;
d->dmy = TRUE;
}
GDateWeekday
g_date_weekday (GDate *d)
{
g_return_val_if_fail (d != NULL, G_DATE_BAD_WEEKDAY);
g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_WEEKDAY);
if (!d->julian)
{
g_date_update_julian (d);
}
g_return_val_if_fail (d->julian, G_DATE_BAD_WEEKDAY);
return ((d->julian_days - 1) % 7) + 1;
}
GDateMonth
g_date_month (GDate *d)
{
g_return_val_if_fail (d != NULL, G_DATE_BAD_MONTH);
g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_MONTH);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, G_DATE_BAD_MONTH);
return d->month;
}
GDateYear
g_date_year (GDate *d)
{
g_return_val_if_fail (d != NULL, G_DATE_BAD_YEAR);
g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_YEAR);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, G_DATE_BAD_YEAR);
return d->year;
}
GDateDay
g_date_day (GDate *d)
{
g_return_val_if_fail (d != NULL, G_DATE_BAD_DAY);
g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_DAY);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, G_DATE_BAD_DAY);
return d->day;
}
guint32
g_date_julian (GDate *d)
{
g_return_val_if_fail (d != NULL, G_DATE_BAD_JULIAN);
g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_JULIAN);
if (!d->julian)
{
g_date_update_julian (d);
}
g_return_val_if_fail (d->julian, G_DATE_BAD_JULIAN);
return d->julian_days;
}
guint
g_date_day_of_year (GDate *d)
{
gint index;
g_return_val_if_fail (d != NULL, 0);
g_return_val_if_fail (g_date_valid (d), 0);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, 0);
index = g_date_is_leap_year (d->year) ? 1 : 0;
return (days_in_year[index][d->month] + d->day);
}
guint
g_date_monday_week_of_year (GDate *d)
{
GDateWeekday wd;
guint day;
GDate first;
g_return_val_if_fail (d != NULL, 0);
g_return_val_if_fail (g_date_valid (d), 0);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, 0);
g_date_clear (&first, 1);
g_date_set_dmy (&first, 1, 1, d->year);
wd = g_date_weekday (&first) - 1; /* make Monday day 0 */
day = g_date_day_of_year (d) - 1;
return ((day + wd)/7U + (wd == 0 ? 1 : 0));
}
guint
g_date_sunday_week_of_year (GDate *d)
{
GDateWeekday wd;
guint day;
GDate first;
g_return_val_if_fail (d != NULL, 0);
g_return_val_if_fail (g_date_valid (d), 0);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, 0);
g_date_clear (&first, 1);
g_date_set_dmy (&first, 1, 1, d->year);
wd = g_date_weekday (&first);
if (wd == 7) wd = 0; /* make Sunday day 0 */
day = g_date_day_of_year (d) - 1;
return ((day + wd)/7U + (wd == 0 ? 1 : 0));
}
void
g_date_clear (GDate *d, guint ndates)
{
g_return_if_fail (d != NULL);
g_return_if_fail (ndates != 0);
memset (d, 0x0, ndates*sizeof (GDate));
}
G_LOCK_DEFINE_STATIC (g_date_global);
/* These are for the parser, output to the user should use *
* g_date_strftime () - this creates more never-freed memory to annoy
* all those memory debugger users. :-)
*/
static gchar *long_month_names[13] =
{
"Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
};
static gchar *short_month_names[13] =
{
"Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
};
/* This tells us if we need to update the parse info */
static gchar *current_locale = NULL;
/* order of these in the current locale */
static GDateDMY dmy_order[3] =
{
G_DATE_DAY, G_DATE_MONTH, G_DATE_YEAR
};
/* Where to chop two-digit years: i.e., for the 1930 default, numbers
* 29 and below are counted as in the year 2000, numbers 30 and above
* are counted as in the year 1900.
*/
static GDateYear twodigit_start_year = 1930;
/* It is impossible to enter a year between 1 AD and 99 AD with this
* in effect.
*/
static gboolean using_twodigit_years = FALSE;
struct _GDateParseTokens {
gint num_ints;
gint n[3];
guint month;
};
typedef struct _GDateParseTokens GDateParseTokens;
#define NUM_LEN 10
/* HOLDS: g_date_global_lock */
static void
g_date_fill_parse_tokens (const gchar *str, GDateParseTokens *pt)
{
gchar num[4][NUM_LEN+1];
gint i;
const gchar *s;
/* We count 4, but store 3; so we can give an error
* if there are 4.
*/
num[0][0] = num[1][0] = num[2][0] = num[3][0] = '\0';
s = str;
pt->num_ints = 0;
while (*s && pt->num_ints < 4)
{
i = 0;
while (*s && isdigit (*s) && i <= NUM_LEN)
{
num[pt->num_ints][i] = *s;
++s;
++i;
}
if (i > 0)
{
num[pt->num_ints][i] = '\0';
++(pt->num_ints);
}
if (*s == '\0') break;
++s;
}
pt->n[0] = pt->num_ints > 0 ? atoi (num[0]) : 0;
pt->n[1] = pt->num_ints > 1 ? atoi (num[1]) : 0;
pt->n[2] = pt->num_ints > 2 ? atoi (num[2]) : 0;
pt->month = G_DATE_BAD_MONTH;
if (pt->num_ints < 3)
{
gchar lcstr[128];
int i = 1;
strncpy (lcstr, str, 127);
g_strdown (lcstr);
while (i < 13)
{
if (long_month_names[i] != NULL)
{
const gchar *found = strstr (lcstr, long_month_names[i]);
if (found != NULL)
{
pt->month = i;
return;
}
}
if (short_month_names[i] != NULL)
{
const gchar *found = strstr (lcstr, short_month_names[i]);
if (found != NULL)
{
pt->month = i;
return;
}
}
++i;
}
}
}
/* HOLDS: g_date_global_lock */
static void
g_date_prepare_to_parse (const gchar *str, GDateParseTokens *pt)
{
const gchar *locale = setlocale (LC_TIME, NULL);
gboolean recompute_localeinfo = FALSE;
GDate d;
g_return_if_fail (locale != NULL); /* should not happen */
g_date_clear (&d, 1); /* clear for scratch use */
if ( (current_locale == NULL) || (strcmp (locale, current_locale) != 0) )
{
recompute_localeinfo = TRUE; /* Uh, there used to be a reason for the temporary */
}
if (recompute_localeinfo)
{
int i = 1;
GDateParseTokens testpt;
gchar buf[128];
g_free (current_locale); /* still works if current_locale == NULL */
current_locale = g_strdup (locale);
while (i < 13)
{
g_date_set_dmy (&d, 1, i, 1);
g_return_if_fail (g_date_valid (&d));
g_date_strftime (buf, 127, "%b", &d);
g_free (short_month_names[i]);
g_strdown (buf);
short_month_names[i] = g_strdup (buf);
g_date_strftime (buf, 127, "%B", &d);
g_free (long_month_names[i]);
g_strdown (buf);
long_month_names[i] = g_strdup (buf);
++i;
}
/* Determine DMY order */
/* had to pick a random day - don't change this, some strftimes
* are broken on some days, and this one is good so far. */
g_date_set_dmy (&d, 4, 7, 1976);
g_date_strftime (buf, 127, "%x", &d);
g_date_fill_parse_tokens (buf, &testpt);
i = 0;
while (i < testpt.num_ints)
{
switch (testpt.n[i])
{
case 7:
dmy_order[i] = G_DATE_MONTH;
break;
case 4:
dmy_order[i] = G_DATE_DAY;
break;
case 76:
using_twodigit_years = TRUE; /* FALL THRU */
case 1976:
dmy_order[i] = G_DATE_YEAR;
break;
default:
/* leave it unchanged */
break;
}
++i;
}
#ifdef G_ENABLE_DEBUG
g_message ("**GDate prepared a new set of locale-specific parse rules.");
i = 1;
while (i < 13)
{
g_message (" %s %s", long_month_names[i], short_month_names[i]);
++i;
}
if (using_twodigit_years)
{
g_message ("**Using twodigit years with cutoff year: %u", twodigit_start_year);
}
{
gchar *strings[3];
i = 0;
while (i < 3)
{
switch (dmy_order[i])
{
case G_DATE_MONTH:
strings[i] = "Month";
break;
case G_DATE_YEAR:
strings[i] = "Year";
break;
case G_DATE_DAY:
strings[i] = "Day";
break;
default:
strings[i] = NULL;
break;
}
++i;
}
g_message ("**Order: %s, %s, %s", strings[0], strings[1], strings[2]);
g_message ("**Sample date in this locale: `%s'", buf);
}
#endif
}
g_date_fill_parse_tokens (str, pt);
}
void
g_date_set_parse (GDate *d,
const gchar *str)
{
GDateParseTokens pt;
guint m = G_DATE_BAD_MONTH, day = G_DATE_BAD_DAY, y = G_DATE_BAD_YEAR;
g_return_if_fail (d != NULL);
/* set invalid */
g_date_clear (d, 1);
G_LOCK (g_date_global);
g_date_prepare_to_parse (str, &pt);
#ifdef G_ENABLE_DEBUG
g_message ("Found %d ints, `%d' `%d' `%d' and written out month %d",
pt.num_ints, pt.n[0], pt.n[1], pt.n[2], pt.month);
#endif
if (pt.num_ints == 4)
{
G_UNLOCK (g_date_global);
return; /* presumably a typo; bail out. */
}
if (pt.num_ints > 1)
{
int i = 0;
int j = 0;
g_assert (pt.num_ints < 4); /* i.e., it is 2 or 3 */
while (i < pt.num_ints && j < 3)
{
switch (dmy_order[j])
{
case G_DATE_MONTH:
{
if (pt.num_ints == 2 && pt.month != G_DATE_BAD_MONTH)
{
m = pt.month;
++j; /* skip months, but don't skip this number */
continue;
}
else
m = pt.n[i];
}
break;
case G_DATE_DAY:
{
if (pt.num_ints == 2 && pt.month == G_DATE_BAD_MONTH)
{
day = 1;
++j; /* skip days, since we may have month/year */
continue;
}
day = pt.n[i];
}
break;
case G_DATE_YEAR:
{
y = pt.n[i];
if (using_twodigit_years && y < 100)
{
guint two = twodigit_start_year % 100;
guint century = (twodigit_start_year / 100) * 100;
if (y < two)
century += 100;
y += century;
}
}
break;
default:
break;
}
++i;
++j;
}
if (pt.num_ints == 3 && !g_date_valid_dmy (day, m, y))
{
/* Try YYYY MM DD */
y = pt.n[0];
m = pt.n[1];
day = pt.n[2];
if (using_twodigit_years && y < 100)
y = G_DATE_BAD_YEAR; /* avoids ambiguity */
}
}
else if (pt.num_ints == 1)
{
if (pt.month != G_DATE_BAD_MONTH)
{
/* Month name and year? */
m = pt.month;
day = 1;
y = pt.n[0];
}
else
{
/* Try yyyymmdd and yymmdd */
m = (pt.n[0]/100) % 100;
day = pt.n[0] % 100;
y = pt.n[0]/10000;
/* FIXME move this into a separate function */
if (using_twodigit_years && y < 100)
{
guint two = twodigit_start_year % 100;
guint century = (twodigit_start_year / 100) * 100;
if (y < two)
century += 100;
y += century;
}
}
}
/* See if we got anything valid out of all this. */
/* y < 8000 is to catch 19998 style typos; the library is OK up to 65535 or so */
if (y < 8000 && g_date_valid_dmy (day, m, y))
{
d->month = m;
d->day = day;
d->year = y;
d->dmy = TRUE;
}
#ifdef G_ENABLE_DEBUG
else
g_message ("Rejected DMY %u %u %u", day, m, y);
#endif
G_UNLOCK (g_date_global);
}
void
g_date_set_time (GDate *d,
GTime time)
{
time_t t = time;
struct tm tm;
g_return_if_fail (d != NULL);
#ifdef HAVE_LOCALTIME_R
localtime_r (&t, &tm);
#else
{
struct tm *ptm = localtime (&t);
g_assert (ptm);
memcpy ((void *) &tm, (void *) ptm, sizeof(struct tm));
}
#endif
d->julian = FALSE;
d->month = tm.tm_mon + 1;
d->day = tm.tm_mday;
d->year = tm.tm_year + 1900;
g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
d->dmy = TRUE;
}
void
g_date_set_month (GDate *d,
GDateMonth m)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid_month (m));
if (d->julian && !d->dmy) g_date_update_dmy(d);
d->julian = FALSE;
d->month = m;
if (g_date_valid_dmy (d->day, d->month, d->year))
d->dmy = TRUE;
else
d->dmy = FALSE;
}
void
g_date_set_day (GDate *d,
GDateDay day)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid_day (day));
if (d->julian && !d->dmy) g_date_update_dmy(d);
d->julian = FALSE;
d->day = day;
if (g_date_valid_dmy (d->day, d->month, d->year))
d->dmy = TRUE;
else
d->dmy = FALSE;
}
void
g_date_set_year (GDate *d,
GDateYear y)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid_year (y));
if (d->julian && !d->dmy) g_date_update_dmy(d);
d->julian = FALSE;
d->year = y;
if (g_date_valid_dmy (d->day, d->month, d->year))
d->dmy = TRUE;
else
d->dmy = FALSE;
}
void
g_date_set_dmy (GDate *d,
GDateDay day,
GDateMonth m,
GDateYear y)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid_dmy (day, m, y));
d->julian = FALSE;
d->month = m;
d->day = day;
d->year = y;
d->dmy = TRUE;
}
void
g_date_set_julian (GDate *d, guint32 j)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid_julian (j));
d->julian_days = j;
d->julian = TRUE;
d->dmy = FALSE;
}
gboolean
g_date_is_first_of_month (GDate *d)
{
g_return_val_if_fail (d != NULL, FALSE);
g_return_val_if_fail (g_date_valid (d), FALSE);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, FALSE);
if (d->day == 1) return TRUE;
else return FALSE;
}
gboolean
g_date_is_last_of_month (GDate *d)
{
gint index;
g_return_val_if_fail (d != NULL, FALSE);
g_return_val_if_fail (g_date_valid (d), FALSE);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_val_if_fail (d->dmy, FALSE);
index = g_date_is_leap_year (d->year) ? 1 : 0;
if (d->day == days_in_months[index][d->month]) return TRUE;
else return FALSE;
}
void
g_date_add_days (GDate *d, guint ndays)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid (d));
if (!d->julian)
{
g_date_update_julian (d);
}
g_return_if_fail (d->julian);
d->julian_days += ndays;
d->dmy = FALSE;
}
void
g_date_subtract_days (GDate *d, guint ndays)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid (d));
if (!d->julian)
{
g_date_update_julian (d);
}
g_return_if_fail (d->julian);
g_return_if_fail (d->julian_days > ndays);
d->julian_days -= ndays;
d->dmy = FALSE;
}
void
g_date_add_months (GDate *d,
guint nmonths)
{
guint years, months;
gint index;
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid (d));
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_if_fail (d->dmy);
nmonths += d->month - 1;
years = nmonths/12;
months = nmonths%12;
d->month = months + 1;
d->year += years;
index = g_date_is_leap_year (d->year) ? 1 : 0;
if (d->day > days_in_months[index][d->month])
d->day = days_in_months[index][d->month];
d->julian = FALSE;
g_return_if_fail (g_date_valid (d));
}
void
g_date_subtract_months (GDate *d,
guint nmonths)
{
guint years, months;
gint index;
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid (d));
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_if_fail (d->dmy);
years = nmonths/12;
months = nmonths%12;
g_return_if_fail (d->year > years);
d->year -= years;
if (d->month > months) d->month -= months;
else
{
months -= d->month;
d->month = 12 - months;
d->year -= 1;
}
index = g_date_is_leap_year (d->year) ? 1 : 0;
if (d->day > days_in_months[index][d->month])
d->day = days_in_months[index][d->month];
d->julian = FALSE;
g_return_if_fail (g_date_valid (d));
}
void
g_date_add_years (GDate *d,
guint nyears)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid (d));
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_if_fail (d->dmy);
d->year += nyears;
if (d->month == 2 && d->day == 29)
{
if (!g_date_is_leap_year (d->year))
{
d->day = 28;
}
}
d->julian = FALSE;
}
void
g_date_subtract_years (GDate *d,
guint nyears)
{
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid (d));
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_if_fail (d->dmy);
g_return_if_fail (d->year > nyears);
d->year -= nyears;
if (d->month == 2 && d->day == 29)
{
if (!g_date_is_leap_year (d->year))
{
d->day = 28;
}
}
d->julian = FALSE;
}
gboolean
g_date_is_leap_year (GDateYear year)
{
g_return_val_if_fail (g_date_valid_year (year), FALSE);
return ( (((year % 4) == 0) && ((year % 100) != 0)) ||
(year % 400) == 0 );
}
guint8
g_date_days_in_month (GDateMonth month,
GDateYear year)
{
gint index;
g_return_val_if_fail (g_date_valid_year (year), 0);
g_return_val_if_fail (g_date_valid_month (month), 0);
index = g_date_is_leap_year (year) ? 1 : 0;
return days_in_months[index][month];
}
guint8
g_date_monday_weeks_in_year (GDateYear year)
{
GDate d;
g_return_val_if_fail (g_date_valid_year (year), 0);
g_date_clear (&d, 1);
g_date_set_dmy (&d, 1, 1, year);
if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
g_date_set_dmy (&d, 31, 12, year);
if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
if (g_date_is_leap_year (year))
{
g_date_set_dmy (&d, 2, 1, year);
if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
g_date_set_dmy (&d, 30, 12, year);
if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
}
return 52;
}
guint8
g_date_sunday_weeks_in_year (GDateYear year)
{
GDate d;
g_return_val_if_fail (g_date_valid_year (year), 0);
g_date_clear (&d, 1);
g_date_set_dmy (&d, 1, 1, year);
if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
g_date_set_dmy (&d, 31, 12, year);
if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
if (g_date_is_leap_year (year))
{
g_date_set_dmy (&d, 2, 1, year);
if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
g_date_set_dmy (&d, 30, 12, year);
if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
}
return 52;
}
gint
g_date_compare (GDate *lhs,
GDate *rhs)
{
g_return_val_if_fail (lhs != NULL, 0);
g_return_val_if_fail (rhs != NULL, 0);
g_return_val_if_fail (g_date_valid (lhs), 0);
g_return_val_if_fail (g_date_valid (rhs), 0);
/* Remember the self-comparison case! I think it works right now. */
while (TRUE)
{
if (lhs->julian && rhs->julian)
{
if (lhs->julian_days < rhs->julian_days) return -1;
else if (lhs->julian_days > rhs->julian_days) return 1;
else return 0;
}
else if (lhs->dmy && rhs->dmy)
{
if (lhs->year < rhs->year) return -1;
else if (lhs->year > rhs->year) return 1;
else
{
if (lhs->month < rhs->month) return -1;
else if (lhs->month > rhs->month) return 1;
else
{
if (lhs->day < rhs->day) return -1;
else if (lhs->day > rhs->day) return 1;
else return 0;
}
}
}
else
{
if (!lhs->julian) g_date_update_julian (lhs);
if (!rhs->julian) g_date_update_julian (rhs);
g_return_val_if_fail (lhs->julian, 0);
g_return_val_if_fail (rhs->julian, 0);
}
}
return 0; /* warnings */
}
void
g_date_to_struct_tm (GDate *d,
struct tm *tm)
{
GDateWeekday day;
g_return_if_fail (d != NULL);
g_return_if_fail (g_date_valid (d));
g_return_if_fail (tm != NULL);
if (!d->dmy)
{
g_date_update_dmy (d);
}
g_return_if_fail (d->dmy);
/* zero all the irrelevant fields to be sure they're valid */
/* On Linux and maybe other systems, there are weird non-POSIX
* fields on the end of struct tm that choke strftime if they
* contain garbage. So we need to 0 the entire struct, not just the
* fields we know to exist.
*/
memset (tm, 0x0, sizeof (struct tm));
tm->tm_mday = d->day;
tm->tm_mon = d->month - 1; /* 0-11 goes in tm */
tm->tm_year = ((int)d->year) - 1900; /* X/Open says tm_year can be negative */
day = g_date_weekday (d);
if (day == 7) day = 0; /* struct tm wants days since Sunday, so Sunday is 0 */
tm->tm_wday = (int)day;
tm->tm_yday = g_date_day_of_year (d) - 1; /* 0 to 365 */
tm->tm_isdst = -1; /* -1 means "information not available" */
}
gsize
g_date_strftime (gchar *s,
gsize slen,
const gchar *format,
GDate *d)
{
struct tm tm;
gsize retval;
g_return_val_if_fail (d != NULL, 0);
g_return_val_if_fail (g_date_valid (d), 0);
g_return_val_if_fail (slen > 0, 0);
g_return_val_if_fail (format != 0, 0);
g_return_val_if_fail (s != 0, 0);
g_date_to_struct_tm (d, &tm);
retval = strftime (s, slen, format, &tm);
if (retval == 0)
{
/* If retval == 0, the contents of s are undefined. We define
* them.
*/
s[0] = '\0';
}
return retval;
}
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