gdate.c

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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 Lesser 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser 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 1997-2000.  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
 */

#define DEBUG_MSG(x)	/* */
#ifdef G_ENABLE_DEBUG
/* #define DEBUG_MSG(args)	g_message args ; */
#endif

#ifdef HAVE_CONFIG_H
#include "glibconfig.h"
#endif

#include "glib.h"

#include <time.h>
#include <string.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 (const 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 (const GDate *const_d)
{
  GDate *d = (GDate *) const_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 (const GDate *const_d)
{
  GDate *d = (GDate *) const_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_get_weekday (const 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_get_month (const 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_get_year (const 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_get_day (const 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_get_julian (const 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_get_day_of_year (const 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_get_monday_week_of_year (const 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_get_weekday (&first) - 1; /* make Monday day 0 */
  day = g_date_get_day_of_year (d) - 1;
  
  return ((day + wd)/7U + (wd == 0 ? 1 : 0));
}

guint        
g_date_get_sunday_week_of_year (const 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_get_weekday (&first);
  if (wd == 7) wd = 0; /* make Sunday day 0 */
  day = g_date_get_day_of_year (d) - 1;
  
  return ((day + wd)/7U + (wd == 0 ? 1 : 0));
}

gint
g_date_days_between (const GDate *d1,
		     const GDate *d2)
{
  g_return_val_if_fail (d1 != NULL, 0);
  g_return_val_if_fail (d2 != NULL, 0);

  g_return_val_if_fail (g_date_valid (d1), 0);
  g_return_val_if_fail (g_date_valid (d2), 0);

  return (gint)g_date_get_julian (d2) - (gint)g_date_get_julian (d1);
}

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 guchar *s;
  
  /* We count 4, but store 3; so we can give an error
   * if there are 4.
   */