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 */
}
guint32
g_date_get_julian (const GDate *d)
{
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;
}
GDateWeekday
g_date_get_weekday (const GDate *d)
{
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;
}
void
g_date_add_days (GDate *d,
guint ndays)
{
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;
}
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;
}
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;
}
/**
* g_date_get_iso8601_week_of_year:
* @date: a valid #GDate
*
* Returns the week of the year, where weeks are interpreted according
* to ISO 8601.
*
* Returns: ISO 8601 week number of the year.
*
* Since: 2.6
**/
guint
g_date_get_iso8601_week_of_year (const GDate *d)
{
guint j, d4, L, d1, w;
g_return_val_if_fail (g_date_valid (d), 0);
if (!d->julian)
g_date_update_julian (d);
g_return_val_if_fail (d->julian, 0);
/* 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.
*/
j = d->julian_days + 1721425;
d4 = (j + 31741 - (j % 7)) % 146097 % 36524 % 1461;
L = d4 / 1460;
d1 = ((d4 - L) % 365) + L;
w = d1 / 7 + 1;
return w;
}