+/* GDate
+ *
+ * Date calculations (not time for now, to be resolved). These are a
+ * mutant combination of Steffen Beyer's DateCalc routines
+ * (http://www.perl.com/CPAN/authors/id/STBEY/) and Jon Trowbridge's
+ * date routines (written for in-house software). Written by Havoc
+ * Pennington <hp@pobox.com>
+ */
+
+typedef guint16 GDateYear;
+typedef guint8 GDateDay; /* day of the month */
+typedef struct _GDate GDate;
+/* make struct tm known without having to include time.h */
+struct tm;
+
+/* enum used to specify order of appearance in parsed date strings */
+typedef enum
+{
+ G_DATE_DAY = 0,
+ G_DATE_MONTH = 1,
+ G_DATE_YEAR = 2
+} GDateDMY;
+
+/* actual week and month values */
+typedef enum
+{
+ G_DATE_BAD_WEEKDAY = 0,
+ G_DATE_MONDAY = 1,
+ G_DATE_TUESDAY = 2,
+ G_DATE_WEDNESDAY = 3,
+ G_DATE_THURSDAY = 4,
+ G_DATE_FRIDAY = 5,
+ G_DATE_SATURDAY = 6,
+ G_DATE_SUNDAY = 7
+} GDateWeekday;
+typedef enum
+{
+ G_DATE_BAD_MONTH = 0,
+ G_DATE_JANUARY = 1,
+ G_DATE_FEBRUARY = 2,
+ G_DATE_MARCH = 3,
+ G_DATE_APRIL = 4,
+ G_DATE_MAY = 5,
+ G_DATE_JUNE = 6,
+ G_DATE_JULY = 7,
+ G_DATE_AUGUST = 8,
+ G_DATE_SEPTEMBER = 9,
+ G_DATE_OCTOBER = 10,
+ G_DATE_NOVEMBER = 11,
+ G_DATE_DECEMBER = 12
+} GDateMonth;
+
+#define G_DATE_BAD_JULIAN 0U
+#define G_DATE_BAD_DAY 0U
+#define G_DATE_BAD_YEAR 0U
+
+/* Note: directly manipulating structs is generally a bad idea, but
+ * in this case it's an *incredibly* bad idea, because all or part
+ * of this struct can be invalid at any given time. Use the functions,
+ * or you will get hosed, I promise.
+ */
+struct _GDate
+{
+ guint julian_days : 32; /* julian days representation - we use a
+ * bitfield hoping that 64 bit platforms
+ * will pack this whole struct in one big
+ * int
+ */
+
+ guint julian : 1; /* julian is valid */
+ guint dmy : 1; /* dmy is valid */
+
+ /* DMY representation */
+ guint day : 6;
+ guint month : 4;
+ guint year : 16;
+};
+
+/* g_date_new() returns an invalid date, you then have to _set() stuff
+ * to get a usable object. You can also allocate a GDate statically,
+ * then call g_date_clear() to initialize.
+ */
+GDate* g_date_new (void);
+GDate* g_date_new_dmy (GDateDay day,
+ GDateMonth month,
+ GDateYear year);
+GDate* g_date_new_julian (guint32 julian_day);
+void g_date_free (GDate *date);
+
+/* check g_date_valid() after doing an operation that might fail, like
+ * _parse. Almost all g_date operations are undefined on invalid
+ * dates (the exceptions are the mutators, since you need those to
+ * return to validity).
+ */
+gboolean g_date_valid (GDate *date);
+gboolean g_date_valid_day (GDateDay day);
+gboolean g_date_valid_month (GDateMonth month);
+gboolean g_date_valid_year (GDateYear year);
+gboolean g_date_valid_weekday (GDateWeekday weekday);
+gboolean g_date_valid_julian (guint32 julian_date);
+gboolean g_date_valid_dmy (GDateDay day,
+ GDateMonth month,
+ GDateYear year);
+
+GDateWeekday g_date_weekday (GDate *date);
+GDateMonth g_date_month (GDate *date);
+GDateYear g_date_year (GDate *date);
+GDateDay g_date_day (GDate *date);
+guint32 g_date_julian (GDate *date);
+guint g_date_day_of_year (GDate *date);
+
+/* First monday/sunday is the start of week 1; if we haven't reached
+ * that day, return 0. These are not ISO weeks of the year; that
+ * routine needs to be added.
+ * these functions return the number of weeks, starting on the
+ * corrsponding day
+ */
+guint g_date_monday_week_of_year (GDate *date);
+guint g_date_sunday_week_of_year (GDate *date);
+
+/* If you create a static date struct you need to clear it to get it
+ * in a sane state before use. You can clear a whole array at
+ * once with the ndates argument.
+ */
+void g_date_clear (GDate *date,
+ guint n_dates);
+
+/* The parse routine is meant for dates typed in by a user, so it
+ * permits many formats but tries to catch common typos. If your data
+ * needs to be strictly validated, it is not an appropriate function.
+ */
+void g_date_set_parse (GDate *date,
+ const gchar *str);
+void g_date_set_time (GDate *date,
+ GTime time);
+void g_date_set_month (GDate *date,
+ GDateMonth month);
+void g_date_set_day (GDate *date,
+ GDateDay day);
+void g_date_set_year (GDate *date,
+ GDateYear year);
+void g_date_set_dmy (GDate *date,
+ GDateDay day,
+ GDateMonth month,
+ GDateYear y);
+void g_date_set_julian (GDate *date,
+ guint32 julian_date);
+gboolean g_date_is_first_of_month (GDate *date);
+gboolean g_date_is_last_of_month (GDate *date);
+
+/* To go forward by some number of weeks just go forward weeks*7 days */
+void g_date_add_days (GDate *date,
+ guint n_days);
+void g_date_subtract_days (GDate *date,
+ guint n_days);
+
+/* If you add/sub months while day > 28, the day might change */
+void g_date_add_months (GDate *date,
+ guint n_months);
+void g_date_subtract_months (GDate *date,
+ guint n_months);
+
+/* If it's feb 29, changing years can move you to the 28th */
+void g_date_add_years (GDate *date,
+ guint n_years);
+void g_date_subtract_years (GDate *date,
+ guint n_years);
+gboolean g_date_is_leap_year (GDateYear year);
+guint8 g_date_days_in_month (GDateMonth month,
+ GDateYear year);
+guint8 g_date_monday_weeks_in_year (GDateYear year);
+guint8 g_date_sunday_weeks_in_year (GDateYear year);
+
+/* qsort-friendly (with a cast...) */
+gint g_date_compare (GDate *lhs,
+ GDate *rhs);
+void g_date_to_struct_tm (GDate *date,
+ struct tm *tm);
+
+/* Just like strftime() except you can only use date-related formats.
+ * Using a time format is undefined.
+ */
+gsize g_date_strftime (gchar *s,
+ gsize slen,
+ const gchar *format,
+ GDate *date);
+
+
+/* GRelation
+ *
+ * Indexed Relations. Imagine a really simple table in a