glib/gdate.c

   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 /*
  28  * MT safe
  29  */
  30
  31 #include "config.h"
  32
  33 #define DEBUG_MSG(x)    /* */
  34 #ifdef G_ENABLE_DEBUG
  35 /* #define DEBUG_MSG(args)      g_message args ; */
  36 #endif
  37
  38 #include "glib.h"
  39
  40 #include <time.h>
  41 #include <string.h>
  42 #include <stdlib.h>
  43 #include <locale.h>
  44
  45 #include "galias.h"
  46
  47 GDate*
  48 g_date_new (void)
  49 {
  50   GDate *d = g_new0 (GDate, 1); /* happily, 0 is the invalid flag for everything. */
  51
  52   return d;
  53 }
  54
  55 GDate*
  56 g_date_new_dmy (GDateDay day, GDateMonth m, GDateYear y)
  57 {
  58   GDate *d;
  59   g_return_val_if_fail (g_date_valid_dmy (day, m, y), NULL);
  60
  61   d = g_new (GDate, 1);
  62
  63   d->julian = FALSE;
  64   d->dmy    = TRUE;
  65
  66   d->month = m;
  67   d->day   = day;
  68   d->year  = y;
  69
  70   g_assert (g_date_valid (d));
  71
  72   return d;
  73 }
  74
  75 GDate*
  76 g_date_new_julian (guint32 j)
  77 {
  78   GDate *d;
  79   g_return_val_if_fail (g_date_valid_julian (j), NULL);
  80
  81   d = g_new (GDate, 1);
  82
  83   d->julian = TRUE;
  84   d->dmy    = FALSE;
  85
  86   d->julian_days = j;
  87
  88   g_assert (g_date_valid (d));
  89
  90   return d;
  91 }
  92
  93 void
  94 g_date_free (GDate *d)
  95 {
  96   g_return_if_fail (d != NULL);
  97
  98   g_free (d);
  99 }
 100
 101 gboolean
 102 g_date_valid (const GDate *d)
 103 {
 104   g_return_val_if_fail (d != NULL, FALSE);
 105
 106   return (d->julian || d->dmy);
 107 }
 108
 109 static const guint8 days_in_months[2][13] =
 110 {  /* error, jan feb mar apr may jun jul aug sep oct nov dec */
 111   {  0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
 112   {  0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } /* leap year */
 113 };
 114
 115 static const guint16 days_in_year[2][14] =
 116 {  /* 0, jan feb mar apr may  jun  jul  aug  sep  oct  nov  dec */
 117   {  0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
 118   {  0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
 119 };
 120
 121 gboolean
 122 g_date_valid_month (GDateMonth   m)
 123 {
 124   return ( (m > G_DATE_BAD_MONTH) && (m < 13) );
 125 }
 126
 127 gboolean
 128 g_date_valid_year (GDateYear    y)
 129 {
 130   return ( y > G_DATE_BAD_YEAR );
 131 }
 132
 133 gboolean
 134 g_date_valid_day (GDateDay     d)
 135 {
 136   return ( (d > G_DATE_BAD_DAY) && (d < 32) );
 137 }
 138
 139 gboolean
 140 g_date_valid_weekday (GDateWeekday w)
 141 {
 142   return ( (w > G_DATE_BAD_WEEKDAY) && (w < 8) );
 143 }
 144
 145 gboolean
 146 g_date_valid_julian (guint32      j)
 147 {
 148   return (j > G_DATE_BAD_JULIAN);
 149 }
 150
 151 gboolean
 152 g_date_valid_dmy (GDateDay     d,
 153                   GDateMonth   m,
 154                   GDateYear    y)
 155 {
 156   return ( (m > G_DATE_BAD_MONTH) &&
 157            (m < 13)               &&
 158            (d > G_DATE_BAD_DAY)   &&
 159            (y > G_DATE_BAD_YEAR)  &&   /* must check before using g_date_is_leap_year */
 160            (d <=  (g_date_is_leap_year (y) ?
 161                    days_in_months[1][m] : days_in_months[0][m])) );
 162 }
 163
 164
 165 /* "Julian days" just means an absolute number of days, where Day 1 ==
 166  *   Jan 1, Year 1
 167  */
 168 static void
 169 g_date_update_julian (const GDate *const_d)
 170 {
 171   GDate *d = (GDate *) const_d;
 172   GDateYear year;
 173   gint index;
 174
 175   g_return_if_fail (d != NULL);
 176   g_return_if_fail (d->dmy);
 177   g_return_if_fail (!d->julian);
 178   g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
 179
 180   /* What we actually do is: multiply years * 365 days in the year,
 181    *  add the number of years divided by 4, subtract the number of
 182    *  years divided by 100 and add the number of years divided by 400,
 183    *  which accounts for leap year stuff. Code from Steffen Beyer's
 184    *  DateCalc.
 185    */
 186
 187   year = d->year - 1; /* we know d->year > 0 since it's valid */
 188
 189   d->julian_days = year * 365U;
 190   d->julian_days += (year >>= 2); /* divide by 4 and add */
 191   d->julian_days -= (year /= 25); /* divides original # years by 100 */
 192   d->julian_days += year >> 2;    /* divides by 4, which divides original by 400 */
 193
 194   index = g_date_is_leap_year (d->year) ? 1 : 0;
 195
 196   d->julian_days += days_in_year[index][d->month] + d->day;
 197
 198   g_return_if_fail (g_date_valid_julian (d->julian_days));
 199
 200   d->julian = TRUE;
 201 }
 202
 203 static void
 204 g_date_update_dmy (const GDate *const_d)
 205 {
 206   GDate *d = (GDate *) const_d;
 207   GDateYear y;
 208   GDateMonth m;
 209   GDateDay day;
 210
 211   guint32 A, B, C, D, E, M;
 212
 213   g_return_if_fail (d != NULL);
 214   g_return_if_fail (d->julian);
 215   g_return_if_fail (!d->dmy);
 216   g_return_if_fail (g_date_valid_julian (d->julian_days));
 217
 218   /* Formula taken from the Calendar FAQ; the formula was for the
 219    *  Julian Period which starts on 1 January 4713 BC, so we add
 220    *  1,721,425 to the number of days before doing the formula.
 221    *
 222    * I'm sure this can be simplified for our 1 January 1 AD period
 223    * start, but I can't figure out how to unpack the formula.
 224    */
 225
 226   A = d->julian_days + 1721425 + 32045;
 227   B = ( 4 *(A + 36524) )/ 146097 - 1;
 228   C = A - (146097 * B)/4;
 229   D = ( 4 * (C + 365) ) / 1461 - 1;
 230   E = C - ((1461*D) / 4);
 231   M = (5 * (E - 1) + 2)/153;
 232
 233   m = M + 3 - (12*(M/10));
 234   day = E - (153*M + 2)/5;
 235   y = 100 * B + D - 4800 + (M/10);
 236
 237 #ifdef G_ENABLE_DEBUG
 238   if (!g_date_valid_dmy (day, m, y))
 239     {
 240       g_warning ("\nOOPS julian: %u  computed dmy: %u %u %u\n",
 241                  d->julian_days, day, m, y);
 242     }
 243 #endif
 244
 245   d->month = m;
 246   d->day   = day;
 247   d->year  = y;
 248
 249   d->dmy = TRUE;
 250 }
 251
 252 GDateWeekday
 253 g_date_get_weekday (const GDate *d)
 254 {
 255   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_WEEKDAY);
 256
 257   if (!d->julian)
 258     {
 259       g_date_update_julian (d);
 260     }
 261   g_return_val_if_fail (d->julian, G_DATE_BAD_WEEKDAY);
 262
 263   return ((d->julian_days - 1) % 7) + 1;
 264 }
 265
 266 GDateMonth
 267 g_date_get_month (const GDate *d)
 268 {
 269   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_MONTH);
 270
 271   if (!d->dmy)
 272     {
 273       g_date_update_dmy (d);
 274     }
 275   g_return_val_if_fail (d->dmy, G_DATE_BAD_MONTH);
 276
 277   return d->month;
 278 }
 279
 280 GDateYear
 281 g_date_get_year (const GDate *d)
 282 {
 283   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_YEAR);
 284
 285   if (!d->dmy)
 286     {
 287       g_date_update_dmy (d);
 288     }
 289   g_return_val_if_fail (d->dmy, G_DATE_BAD_YEAR);
 290
 291   return d->year;
 292 }
 293
 294 GDateDay
 295 g_date_get_day (const GDate *d)
 296 {
 297   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_DAY);
 298
 299   if (!d->dmy)
 300     {
 301       g_date_update_dmy (d);
 302     }
 303   g_return_val_if_fail (d->dmy, G_DATE_BAD_DAY);
 304
 305   return d->day;
 306 }
 307
 308 guint32
 309 g_date_get_julian (const GDate *d)
 310 {
 311   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_JULIAN);
 312
 313   if (!d->julian)
 314     {
 315       g_date_update_julian (d);
 316     }
 317   g_return_val_if_fail (d->julian, G_DATE_BAD_JULIAN);
 318
 319   return d->julian_days;
 320 }
 321
 322 guint
 323 g_date_get_day_of_year (const GDate *d)
 324 {
 325   gint index;
 326
 327   g_return_val_if_fail (g_date_valid (d), 0);
 328
 329   if (!d->dmy)
 330     {
 331       g_date_update_dmy (d);
 332     }
 333   g_return_val_if_fail (d->dmy, 0);
 334
 335   index = g_date_is_leap_year (d->year) ? 1 : 0;
 336
 337   return (days_in_year[index][d->month] + d->day);
 338 }
 339
 340 guint
 341 g_date_get_monday_week_of_year (const GDate *d)
 342 {
 343   GDateWeekday wd;
 344   guint day;
 345   GDate first;
 346
 347   g_return_val_if_fail (g_date_valid (d), 0);
 348
 349   if (!d->dmy)
 350     {
 351       g_date_update_dmy (d);
 352     }
 353   g_return_val_if_fail (d->dmy, 0);
 354
 355   g_date_clear (&first, 1);
 356
 357   g_date_set_dmy (&first, 1, 1, d->year);
 358
 359   wd = g_date_get_weekday (&first) - 1; /* make Monday day 0 */
 360   day = g_date_get_day_of_year (d) - 1;
 361
 362   return ((day + wd)/7U + (wd == 0 ? 1 : 0));
 363 }
 364
 365 guint
 366 g_date_get_sunday_week_of_year (const GDate *d)
 367 {
 368   GDateWeekday wd;
 369   guint day;
 370   GDate first;
 371
 372   g_return_val_if_fail (g_date_valid (d), 0);
 373
 374   if (!d->dmy)
 375     {
 376       g_date_update_dmy (d);
 377     }
 378   g_return_val_if_fail (d->dmy, 0);
 379
 380   g_date_clear (&first, 1);
 381
 382   g_date_set_dmy (&first, 1, 1, d->year);
 383
 384   wd = g_date_get_weekday (&first);
 385   if (wd == 7) wd = 0; /* make Sunday day 0 */
 386   day = g_date_get_day_of_year (d) - 1;
 387
 388   return ((day + wd)/7U + (wd == 0 ? 1 : 0));
 389 }
 390
 391 /**
 392  * g_date_get_iso8601_week_of_year:
 393  * @date: a valid #GDate
 394  *
 395  * Returns the week of the year, where weeks are interpreted according
 396  * to ISO 8601.
 397  *
 398  * Returns: ISO 8601 week number of the year.
 399  *
 400  * Since: 2.6
 401  **/
 402 guint
 403 g_date_get_iso8601_week_of_year (const GDate *d)
 404 {
 405   guint j, d4, L, d1, w;
 406
 407   g_return_val_if_fail (g_date_valid (d), 0);
 408
 409   if (!d->julian)
 410     g_date_update_julian (d);
 411   g_return_val_if_fail (d->julian, 0);
 412
 413   /* Formula taken from the Calendar FAQ; the formula was for the
 414    * Julian Period which starts on 1 January 4713 BC, so we add
 415    * 1,721,425 to the number of days before doing the formula.
 416    */
 417   j  = d->julian + 1721425;
 418   d4 = (j + 31741 - (j % 7)) % 146097 % 36524 % 1461;
 419   L  = d4 / 1460;
 420   d1 = ((d4 - L) % 365) + L;
 421   w  = d1 / 7 + 1;
 422
 423   return w;
 424 }
 425
 426 gint
 427 g_date_days_between (const GDate *d1,
 428                      const GDate *d2)
 429 {
 430   g_return_val_if_fail (g_date_valid (d1), 0);
 431   g_return_val_if_fail (g_date_valid (d2), 0);
 432
 433   return (gint)g_date_get_julian (d2) - (gint)g_date_get_julian (d1);
 434 }
 435
 436 void
 437 g_date_clear (GDate *d, guint ndates)
 438 {
 439   g_return_if_fail (d != NULL);
 440   g_return_if_fail (ndates != 0);
 441
 442   memset (d, 0x0, ndates*sizeof (GDate));
 443 }
 444
 445 G_LOCK_DEFINE_STATIC (g_date_global);
 446
 447 /* These are for the parser, output to the user should use *
 448  * g_date_strftime () - this creates more never-freed memory to annoy
 449  * all those memory debugger users. :-)
 450  */
 451
 452 static gchar *long_month_names[13] =
 453 {
 454   "Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 455 };
 456
 457 static gchar *short_month_names[13] =
 458 {
 459   "Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 460 };
 461
 462 /* This tells us if we need to update the parse info */
 463 static gchar *current_locale = NULL;
 464
 465 /* order of these in the current locale */
 466 static GDateDMY dmy_order[3] =
 467 {
 468    G_DATE_DAY, G_DATE_MONTH, G_DATE_YEAR
 469 };
 470
 471 /* Where to chop two-digit years: i.e., for the 1930 default, numbers
 472  * 29 and below are counted as in the year 2000, numbers 30 and above
 473  * are counted as in the year 1900.
 474  */
 475
 476 static GDateYear twodigit_start_year = 1930;
 477
 478 /* It is impossible to enter a year between 1 AD and 99 AD with this
 479  * in effect.
 480  */
 481 static gboolean using_twodigit_years = FALSE;
 482
 483 /* Adjustment of locale era to AD, non-zero means using locale era
 484  */
 485 static gint locale_era_adjust = 0;
 486
 487 struct _GDateParseTokens {
 488   gint num_ints;
 489   gint n[3];
 490   guint month;
 491 };
 492
 493 typedef struct _GDateParseTokens GDateParseTokens;
 494
 495 #define NUM_LEN 10
 496
 497 /* HOLDS: g_date_global_lock */
 498 static void
 499 g_date_fill_parse_tokens (const gchar *str, GDateParseTokens *pt)
 500 {
 501   gchar num[4][NUM_LEN+1];
 502   gint i;
 503   const guchar *s;
 504
 505   /* We count 4, but store 3; so we can give an error
 506    * if there are 4.
 507    */
 508   num[0][0] = num[1][0] = num[2][0] = num[3][0] = '\0';
 509
 510   s = (const guchar *) str;
 511   pt->num_ints = 0;
 512   while (*s && pt->num_ints < 4)
 513     {
 514
 515       i = 0;
 516       while (*s && g_ascii_isdigit (*s) && i <= NUM_LEN)
 517         {
 518           num[pt->num_ints][i] = *s;
 519           ++s;
 520           ++i;
 521         }
 522
 523       if (i > 0)
 524         {
 525           num[pt->num_ints][i] = '\0';
 526           ++(pt->num_ints);
 527         }
 528
 529       if (*s == '\0') break;
 530
 531       ++s;
 532     }
 533
 534   pt->n[0] = pt->num_ints > 0 ? atoi (num[0]) : 0;
 535   pt->n[1] = pt->num_ints > 1 ? atoi (num[1]) : 0;
 536   pt->n[2] = pt->num_ints > 2 ? atoi (num[2]) : 0;
 537
 538   pt->month = G_DATE_BAD_MONTH;
 539
 540   if (pt->num_ints < 3)
 541     {
 542       gchar *casefold;
 543       gchar *normalized;
 544
 545       casefold = g_utf8_casefold (str, -1);
 546       normalized = g_utf8_normalize (casefold, -1, G_NORMALIZE_ALL);
 547       g_free (casefold);
 548
 549       i = 1;
 550       while (i < 13)
 551         {
 552           if (long_month_names[i] != NULL)
 553             {
 554               const gchar *found = strstr (normalized, long_month_names[i]);
 555
 556               if (found != NULL)
 557                 {
 558                   pt->month = i;
 559                   break;
 560                 }
 561             }
 562
 563           if (short_month_names[i] != NULL)
 564             {
 565               const gchar *found = strstr (normalized, short_month_names[i]);
 566
 567               if (found != NULL)
 568                 {
 569                   pt->month = i;
 570                   break;
 571                 }
 572             }
 573
 574           ++i;
 575         }
 576
 577       g_free (normalized);
 578     }
 579 }
 580
 581 /* HOLDS: g_date_global_lock */
 582 static void
 583 g_date_prepare_to_parse (const gchar *str, GDateParseTokens *pt)
 584 {
 585   const gchar *locale = setlocale (LC_TIME, NULL);
 586   gboolean recompute_localeinfo = FALSE;
 587   GDate d;
 588
 589   g_return_if_fail (locale != NULL); /* should not happen */
 590
 591   g_date_clear (&d, 1);              /* clear for scratch use */
 592
 593   if ( (current_locale == NULL) || (strcmp (locale, current_locale) != 0) )
 594     {
 595       recompute_localeinfo = TRUE;  /* Uh, there used to be a reason for the temporary */
 596     }
 597
 598   if (recompute_localeinfo)
 599     {
 600       int i = 1;
 601       GDateParseTokens testpt;
 602       gchar buf[128];
 603
 604       g_free (current_locale); /* still works if current_locale == NULL */
 605
 606       current_locale = g_strdup (locale);
 607
 608       while (i < 13)
 609         {
 610           gchar *casefold;
 611
 612           g_date_set_dmy (&d, 1, i, 1);
 613
 614           g_return_if_fail (g_date_valid (&d));
 615
 616           g_date_strftime (buf, 127, "%b", &d);
 617
 618           casefold = g_utf8_casefold (buf, -1);
 619           g_free (short_month_names[i]);
 620           short_month_names[i] = g_utf8_normalize (casefold, -1, G_NORMALIZE_ALL);
 621           g_free (casefold);
 622
 623           g_date_strftime (buf, 127, "%B", &d);
 624           casefold = g_utf8_casefold (buf, -1);
 625           g_free (long_month_names[i]);
 626           long_month_names[i] = g_utf8_normalize (casefold, -1, G_NORMALIZE_ALL);
 627           g_free (casefold);
 628
 629           ++i;
 630         }
 631
 632       /* Determine DMY order */
 633
 634       /* had to pick a random day - don't change this, some strftimes
 635        * are broken on some days, and this one is good so far. */
 636       g_date_set_dmy (&d, 4, 7, 1976);
 637
 638       g_date_strftime (buf, 127, "%x", &d);
 639
 640       g_date_fill_parse_tokens (buf, &testpt);
 641
 642       i = 0;
 643       while (i < testpt.num_ints)
 644         {
 645           switch (testpt.n[i])
 646             {
 647             case 7:
 648               dmy_order[i] = G_DATE_MONTH;
 649               break;
 650             case 4:
 651               dmy_order[i] = G_DATE_DAY;
 652               break;
 653             case 76:
 654               using_twodigit_years = TRUE; /* FALL THRU */
 655             case 1976:
 656               dmy_order[i] = G_DATE_YEAR;
 657               break;
 658             default:
 659               /* assume locale era */
 660               locale_era_adjust = 1976 - testpt.n[i];
 661               dmy_order[i] = G_DATE_YEAR;
 662               break;
 663             }
 664           ++i;
 665         }
 666
 667 #ifdef G_ENABLE_DEBUG
 668       DEBUG_MSG (("**GDate prepared a new set of locale-specific parse rules."));
 669       i = 1;
 670       while (i < 13)
 671         {
 672           DEBUG_MSG (("  %s   %s", long_month_names[i], short_month_names[i]));
 673           ++i;
 674         }
 675       if (using_twodigit_years)
 676         DEBUG_MSG (("**Using twodigit years with cutoff year: %u", twodigit_start_year));
 677       {
 678         gchar *strings[3];
 679         i = 0;
 680         while (i < 3)
 681           {
 682             switch (dmy_order[i])
 683               {
 684               case G_DATE_MONTH:
 685                 strings[i] = "Month";
 686                 break;
 687               case G_DATE_YEAR:
 688                 strings[i] = "Year";
 689                 break;
 690               case G_DATE_DAY:
 691                 strings[i] = "Day";
 692                 break;
 693               default:
 694                 strings[i] = NULL;
 695                 break;
 696               }
 697             ++i;
 698           }
 699         DEBUG_MSG (("**Order: %s, %s, %s", strings[0], strings[1], strings[2]));
 700         DEBUG_MSG (("**Sample date in this locale: `%s'", buf));
 701       }
 702 #endif
 703     }
 704
 705   g_date_fill_parse_tokens (str, pt);
 706 }
 707
 708 void
 709 g_date_set_parse (GDate       *d,
 710                   const gchar *str)
 711 {
 712   GDateParseTokens pt;
 713   guint m = G_DATE_BAD_MONTH, day = G_DATE_BAD_DAY, y = G_DATE_BAD_YEAR;
 714
 715   g_return_if_fail (d != NULL);
 716
 717   /* set invalid */
 718   g_date_clear (d, 1);
 719
 720   G_LOCK (g_date_global);
 721
 722   g_date_prepare_to_parse (str, &pt);
 723
 724   DEBUG_MSG (("Found %d ints, `%d' `%d' `%d' and written out month %d",
 725               pt.num_ints, pt.n[0], pt.n[1], pt.n[2], pt.month));
 726
 727
 728   if (pt.num_ints == 4)
 729     {
 730       G_UNLOCK (g_date_global);
 731       return; /* presumably a typo; bail out. */
 732     }
 733
 734   if (pt.num_ints > 1)
 735     {
 736       int i = 0;
 737       int j = 0;
 738
 739       g_assert (pt.num_ints < 4); /* i.e., it is 2 or 3 */
 740
 741       while (i < pt.num_ints && j < 3)
 742         {
 743           switch (dmy_order[j])
 744             {
 745             case G_DATE_MONTH:
 746             {
 747               if (pt.num_ints == 2 && pt.month != G_DATE_BAD_MONTH)
 748                 {
 749                   m = pt.month;
 750                   ++j;      /* skip months, but don't skip this number */
 751                   continue;
 752                 }
 753               else
 754                 m = pt.n[i];
 755             }
 756             break;
 757             case G_DATE_DAY:
 758             {
 759               if (pt.num_ints == 2 && pt.month == G_DATE_BAD_MONTH)
 760                 {
 761                   day = 1;
 762                   ++j;      /* skip days, since we may have month/year */
 763                   continue;
 764                 }
 765               day = pt.n[i];
 766             }
 767             break;
 768             case G_DATE_YEAR:
 769             {
 770               y  = pt.n[i];
 771
 772               if (locale_era_adjust != 0)
 773                 {
 774                   y += locale_era_adjust;
 775                 }
 776               else if (using_twodigit_years && y < 100)
 777                 {
 778                   guint two     =  twodigit_start_year % 100;
 779                   guint century = (twodigit_start_year / 100) * 100;
 780
 781                   if (y < two)
 782                     century += 100;
 783
 784                   y += century;
 785                 }
 786             }
 787             break;
 788             default:
 789               break;
 790             }
 791
 792           ++i;
 793           ++j;
 794         }
 795
 796
 797       if (pt.num_ints == 3 && !g_date_valid_dmy (day, m, y))
 798         {
 799           /* Try YYYY MM DD */
 800           y   = pt.n[0];
 801           m   = pt.n[1];
 802           day = pt.n[2];
 803
 804           if (using_twodigit_years && y < 100)
 805             y = G_DATE_BAD_YEAR; /* avoids ambiguity */
 806         }
 807       else if (pt.num_ints == 2)
 808         {
 809           if (m == G_DATE_BAD_MONTH && pt.month != G_DATE_BAD_MONTH)
 810             {
 811               m = pt.month;
 812             }
 813         }
 814     }
 815   else if (pt.num_ints == 1)
 816     {
 817       if (pt.month != G_DATE_BAD_MONTH)
 818         {
 819           /* Month name and year? */
 820           m    = pt.month;
 821           day  = 1;
 822           y = pt.n[0];
 823         }
 824       else
 825         {
 826           /* Try yyyymmdd and yymmdd */
 827
 828           m   = (pt.n[0]/100) % 100;
 829           day = pt.n[0] % 100;
 830           y   = pt.n[0]/10000;
 831
 832           /* FIXME move this into a separate function */
 833           if (using_twodigit_years && y < 100)
 834             {
 835               guint two     =  twodigit_start_year % 100;
 836               guint century = (twodigit_start_year / 100) * 100;
 837
 838               if (y < two)
 839                 century += 100;
 840
 841               y += century;
 842             }
 843         }
 844     }
 845
 846   /* See if we got anything valid out of all this. */
 847   /* y < 8000 is to catch 19998 style typos; the library is OK up to 65535 or so */
 848   if (y < 8000 && g_date_valid_dmy (day, m, y))
 849     {
 850       d->month = m;
 851       d->day   = day;
 852       d->year  = y;
 853       d->dmy   = TRUE;
 854     }
 855 #ifdef G_ENABLE_DEBUG
 856   else
 857     DEBUG_MSG (("Rejected DMY %u %u %u", day, m, y));
 858 #endif
 859   G_UNLOCK (g_date_global);
 860 }
 861
 862 void
 863 g_date_set_time (GDate *d,
 864                  GTime  time)
 865 {
 866   time_t t = time;
 867   struct tm tm;
 868
 869   g_return_if_fail (d != NULL);
 870
 871 #ifdef HAVE_LOCALTIME_R
 872   localtime_r (&t, &tm);
 873 #else
 874   {
 875     struct tm *ptm = localtime (&t);
 876
 877     if (ptm == NULL)
 878       {
 879         /* Happens at least in Microsoft's C library if you pass a
 880          * negative time_t. Use 2000-01-01 as default date.
 881          */
 882 #ifndef G_DISABLE_CHECKS
 883         g_return_if_fail_warning (G_LOG_DOMAIN, "g_date_set_time", "ptm != NULL");
 884 #endif
 885
 886         tm.tm_mon = 0;
 887         tm.tm_mday = 1;
 888         tm.tm_year = 100;
 889       }
 890     else
 891       memcpy ((void *) &tm, (void *) ptm, sizeof(struct tm));
 892   }
 893 #endif
 894
 895   d->julian = FALSE;
 896
 897   d->month = tm.tm_mon + 1;
 898   d->day   = tm.tm_mday;
 899   d->year  = tm.tm_year + 1900;
 900
 901   g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
 902
 903   d->dmy    = TRUE;
 904 }
 905
 906 void
 907 g_date_set_month (GDate     *d,
 908                   GDateMonth m)
 909 {
 910   g_return_if_fail (d != NULL);
 911   g_return_if_fail (g_date_valid_month (m));
 912
 913   if (d->julian && !d->dmy) g_date_update_dmy(d);
 914   d->julian = FALSE;
 915
 916   d->month = m;
 917
 918   if (g_date_valid_dmy (d->day, d->month, d->year))
 919     d->dmy = TRUE;
 920   else
 921     d->dmy = FALSE;
 922 }
 923
 924 void
 925 g_date_set_day (GDate     *d,
 926                 GDateDay day)
 927 {
 928   g_return_if_fail (d != NULL);
 929   g_return_if_fail (g_date_valid_day (day));
 930
 931   if (d->julian && !d->dmy) g_date_update_dmy(d);
 932   d->julian = FALSE;
 933
 934   d->day = day;
 935
 936   if (g_date_valid_dmy (d->day, d->month, d->year))
 937     d->dmy = TRUE;
 938   else
 939     d->dmy = FALSE;
 940 }
 941
 942 void
 943 g_date_set_year (GDate     *d,
 944                  GDateYear  y)
 945 {
 946   g_return_if_fail (d != NULL);
 947   g_return_if_fail (g_date_valid_year (y));
 948
 949   if (d->julian && !d->dmy) g_date_update_dmy(d);
 950   d->julian = FALSE;
 951
 952   d->year = y;
 953
 954   if (g_date_valid_dmy (d->day, d->month, d->year))
 955     d->dmy = TRUE;
 956   else
 957     d->dmy = FALSE;
 958 }
 959
 960 void
 961 g_date_set_dmy (GDate     *d,
 962                 GDateDay   day,
 963                 GDateMonth m,
 964                 GDateYear  y)
 965 {
 966   g_return_if_fail (d != NULL);
 967   g_return_if_fail (g_date_valid_dmy (day, m, y));
 968
 969   d->julian = FALSE;
 970
 971   d->month = m;
 972   d->day   = day;
 973   d->year  = y;
 974
 975   d->dmy = TRUE;
 976 }
 977
 978 void
 979 g_date_set_julian (GDate *d, guint32 j)
 980 {
 981   g_return_if_fail (d != NULL);
 982   g_return_if_fail (g_date_valid_julian (j));
 983
 984   d->julian_days = j;
 985   d->julian = TRUE;
 986   d->dmy = FALSE;
 987 }
 988
 989
 990 gboolean
 991 g_date_is_first_of_month (const GDate *d)
 992 {
 993   g_return_val_if_fail (g_date_valid (d), FALSE);
 994
 995   if (!d->dmy)
 996     {
 997       g_date_update_dmy (d);
 998     }
 999   g_return_val_if_fail (d->dmy, FALSE);
1000
1001   if (d->day == 1) return TRUE;
1002   else return FALSE;
1003 }
1004
1005 gboolean
1006 g_date_is_last_of_month (const GDate *d)
1007 {
1008   gint index;
1009
1010   g_return_val_if_fail (g_date_valid (d), FALSE);
1011
1012   if (!d->dmy)
1013     {
1014       g_date_update_dmy (d);
1015     }
1016   g_return_val_if_fail (d->dmy, FALSE);
1017
1018   index = g_date_is_leap_year (d->year) ? 1 : 0;
1019
1020   if (d->day == days_in_months[index][d->month]) return TRUE;
1021   else return FALSE;
1022 }
1023
1024 void
1025 g_date_add_days (GDate *d, guint ndays)
1026 {
1027   g_return_if_fail (g_date_valid (d));
1028
1029   if (!d->julian)
1030     {
1031       g_date_update_julian (d);
1032     }
1033   g_return_if_fail (d->julian);
1034
1035   d->julian_days += ndays;
1036   d->dmy = FALSE;
1037 }
1038
1039 void
1040 g_date_subtract_days (GDate *d, guint ndays)
1041 {
1042   g_return_if_fail (g_date_valid (d));
1043
1044   if (!d->julian)
1045     {
1046       g_date_update_julian (d);
1047     }
1048   g_return_if_fail (d->julian);
1049   g_return_if_fail (d->julian_days > ndays);
1050
1051   d->julian_days -= ndays;
1052   d->dmy = FALSE;
1053 }
1054
1055 void
1056 g_date_add_months (GDate       *d,
1057                    guint        nmonths)
1058 {
1059   guint years, months;
1060   gint index;
1061
1062   g_return_if_fail (g_date_valid (d));
1063
1064   if (!d->dmy)
1065     {
1066       g_date_update_dmy (d);
1067     }
1068   g_return_if_fail (d->dmy);
1069
1070   nmonths += d->month - 1;
1071
1072   years  = nmonths/12;
1073   months = nmonths%12;
1074
1075   d->month = months + 1;
1076   d->year  += years;
1077
1078   index = g_date_is_leap_year (d->year) ? 1 : 0;
1079
1080   if (d->day > days_in_months[index][d->month])
1081     d->day = days_in_months[index][d->month];
1082
1083   d->julian = FALSE;
1084
1085   g_return_if_fail (g_date_valid (d));
1086 }
1087
1088 void
1089 g_date_subtract_months (GDate       *d,
1090                         guint        nmonths)
1091 {
1092   guint years, months;
1093   gint index;
1094
1095   g_return_if_fail (g_date_valid (d));
1096
1097   if (!d->dmy)
1098     {
1099       g_date_update_dmy (d);
1100     }
1101   g_return_if_fail (d->dmy);
1102
1103   years  = nmonths/12;
1104   months = nmonths%12;
1105
1106   g_return_if_fail (d->year > years);
1107
1108   d->year  -= years;
1109
1110   if (d->month > months) d->month -= months;
1111   else
1112     {
1113       months -= d->month;
1114       d->month = 12 - months;
1115       d->year -= 1;
1116     }
1117
1118   index = g_date_is_leap_year (d->year) ? 1 : 0;
1119
1120   if (d->day > days_in_months[index][d->month])
1121     d->day = days_in_months[index][d->month];
1122
1123   d->julian = FALSE;
1124
1125   g_return_if_fail (g_date_valid (d));
1126 }
1127
1128 void
1129 g_date_add_years (GDate       *d,
1130                   guint        nyears)
1131 {
1132   g_return_if_fail (g_date_valid (d));
1133
1134   if (!d->dmy)
1135     {
1136       g_date_update_dmy (d);
1137     }
1138   g_return_if_fail (d->dmy);
1139
1140   d->year += nyears;
1141
1142   if (d->month == 2 && d->day == 29)
1143     {
1144       if (!g_date_is_leap_year (d->year))
1145         {
1146           d->day = 28;
1147         }
1148     }
1149
1150   d->julian = FALSE;
1151 }
1152
1153 void
1154 g_date_subtract_years (GDate       *d,
1155                        guint        nyears)
1156 {
1157   g_return_if_fail (g_date_valid (d));
1158
1159   if (!d->dmy)
1160     {
1161       g_date_update_dmy (d);
1162     }
1163   g_return_if_fail (d->dmy);
1164   g_return_if_fail (d->year > nyears);
1165
1166   d->year -= nyears;
1167
1168   if (d->month == 2 && d->day == 29)
1169     {
1170       if (!g_date_is_leap_year (d->year))
1171         {
1172           d->day = 28;
1173         }
1174     }
1175
1176   d->julian = FALSE;
1177 }
1178
1179
1180 gboolean
1181 g_date_is_leap_year (GDateYear  year)
1182 {
1183   g_return_val_if_fail (g_date_valid_year (year), FALSE);
1184
1185   return ( (((year % 4) == 0) && ((year % 100) != 0)) ||
1186            (year % 400) == 0 );
1187 }
1188
1189 guint8
1190 g_date_get_days_in_month (GDateMonth month,
1191                           GDateYear  year)
1192 {
1193   gint index;
1194
1195   g_return_val_if_fail (g_date_valid_year (year), 0);
1196   g_return_val_if_fail (g_date_valid_month (month), 0);
1197
1198   index = g_date_is_leap_year (year) ? 1 : 0;
1199
1200   return days_in_months[index][month];
1201 }
1202
1203 guint8
1204 g_date_get_monday_weeks_in_year (GDateYear  year)
1205 {
1206   GDate d;
1207
1208   g_return_val_if_fail (g_date_valid_year (year), 0);
1209
1210   g_date_clear (&d, 1);
1211   g_date_set_dmy (&d, 1, 1, year);
1212   if (g_date_get_weekday (&d) == G_DATE_MONDAY) return 53;
1213   g_date_set_dmy (&d, 31, 12, year);
1214   if (g_date_get_weekday (&d) == G_DATE_MONDAY) return 53;
1215   if (g_date_is_leap_year (year))
1216     {
1217       g_date_set_dmy (&d, 2, 1, year);
1218       if (g_date_get_weekday (&d) == G_DATE_MONDAY) return 53;
1219       g_date_set_dmy (&d, 30, 12, year);
1220       if (g_date_get_weekday (&d) == G_DATE_MONDAY) return 53;
1221     }
1222   return 52;
1223 }
1224
1225 guint8
1226 g_date_get_sunday_weeks_in_year (GDateYear  year)
1227 {
1228   GDate d;
1229
1230   g_return_val_if_fail (g_date_valid_year (year), 0);
1231
1232   g_date_clear (&d, 1);
1233   g_date_set_dmy (&d, 1, 1, year);
1234   if (g_date_get_weekday (&d) == G_DATE_SUNDAY) return 53;
1235   g_date_set_dmy (&d, 31, 12, year);
1236   if (g_date_get_weekday (&d) == G_DATE_SUNDAY) return 53;
1237   if (g_date_is_leap_year (year))
1238     {
1239       g_date_set_dmy (&d, 2, 1, year);
1240       if (g_date_get_weekday (&d) == G_DATE_SUNDAY) return 53;
1241       g_date_set_dmy (&d, 30, 12, year);
1242       if (g_date_get_weekday (&d) == G_DATE_SUNDAY) return 53;
1243     }
1244   return 52;
1245 }
1246
1247 gint
1248 g_date_compare (const GDate *lhs,
1249                 const GDate *rhs)
1250 {
1251   g_return_val_if_fail (lhs != NULL, 0);
1252   g_return_val_if_fail (rhs != NULL, 0);
1253   g_return_val_if_fail (g_date_valid (lhs), 0);
1254   g_return_val_if_fail (g_date_valid (rhs), 0);
1255
1256   /* Remember the self-comparison case! I think it works right now. */
1257
1258   while (TRUE)
1259     {
1260
1261       if (lhs->julian && rhs->julian)
1262         {
1263           if (lhs->julian_days < rhs->julian_days) return -1;
1264           else if (lhs->julian_days > rhs->julian_days) return 1;
1265           else                                          return 0;
1266         }
1267       else if (lhs->dmy && rhs->dmy)
1268         {
1269           if (lhs->year < rhs->year)               return -1;
1270           else if (lhs->year > rhs->year)               return 1;
1271           else
1272             {
1273               if (lhs->month < rhs->month)         return -1;
1274               else if (lhs->month > rhs->month)         return 1;
1275               else
1276                 {
1277                   if (lhs->day < rhs->day)              return -1;
1278                   else if (lhs->day > rhs->day)              return 1;
1279                   else                                       return 0;
1280                 }
1281
1282             }
1283
1284         }
1285       else
1286         {
1287           if (!lhs->julian) g_date_update_julian (lhs);
1288           if (!rhs->julian) g_date_update_julian (rhs);
1289           g_return_val_if_fail (lhs->julian, 0);
1290           g_return_val_if_fail (rhs->julian, 0);
1291         }
1292
1293     }
1294   return 0; /* warnings */
1295 }
1296
1297
1298 void
1299 g_date_to_struct_tm (const GDate *d,
1300                      struct tm   *tm)
1301 {
1302   GDateWeekday day;
1303
1304   g_return_if_fail (g_date_valid (d));
1305   g_return_if_fail (tm != NULL);
1306
1307   if (!d->dmy)
1308     {
1309       g_date_update_dmy (d);
1310     }
1311   g_return_if_fail (d->dmy);
1312
1313   /* zero all the irrelevant fields to be sure they're valid */
1314
1315   /* On Linux and maybe other systems, there are weird non-POSIX
1316    * fields on the end of struct tm that choke strftime if they
1317    * contain garbage.  So we need to 0 the entire struct, not just the
1318    * fields we know to exist.
1319    */
1320
1321   memset (tm, 0x0, sizeof (struct tm));
1322
1323   tm->tm_mday = d->day;
1324   tm->tm_mon  = d->month - 1; /* 0-11 goes in tm */
1325   tm->tm_year = ((int)d->year) - 1900; /* X/Open says tm_year can be negative */
1326
1327   day = g_date_get_weekday (d);
1328   if (day == 7) day = 0; /* struct tm wants days since Sunday, so Sunday is 0 */
1329
1330   tm->tm_wday = (int)day;
1331
1332   tm->tm_yday = g_date_get_day_of_year (d) - 1; /* 0 to 365 */
1333   tm->tm_isdst = -1; /* -1 means "information not available" */
1334 }
1335
1336 void
1337 g_date_clamp (GDate *date,
1338               const GDate *min_date,
1339               const GDate *max_date)
1340 {
1341   g_return_if_fail (g_date_valid (date));
1342
1343   if (min_date != NULL)
1344     g_return_if_fail (g_date_valid (min_date));
1345   if (max_date != NULL)
1346     g_return_if_fail (g_date_valid (max_date));
1347   if (min_date != NULL && max_date != NULL)
1348     g_return_if_fail (g_date_compare (min_date, max_date) <= 0);
1349
1350   if (min_date && g_date_compare (date, min_date) < 0)
1351     *date = *min_date;
1352
1353   if (max_date && g_date_compare (max_date, date) < 0)
1354     *date = *max_date;
1355 }
1356
1357 void
1358 g_date_order (GDate *date1,
1359               GDate *date2)
1360 {
1361   g_return_if_fail (g_date_valid (date1));
1362   g_return_if_fail (g_date_valid (date2));
1363
1364   if (g_date_compare (date1, date2) > 0)
1365     {
1366       GDate tmp = *date1;
1367       *date1 = *date2;
1368       *date2 = tmp;
1369     }
1370 }
1371
1372 gsize
1373 g_date_strftime (gchar       *s,
1374                  gsize        slen,
1375                  const gchar *format,
1376                  const GDate *d)
1377 {
1378   struct tm tm;
1379   gsize locale_format_len = 0;
1380   gchar *locale_format;
1381   gsize tmplen;
1382   gchar *tmpbuf;
1383   gsize tmpbufsize;
1384   gsize convlen = 0;
1385   gchar *convbuf;
1386   GError *error = NULL;
1387   gsize retval;
1388
1389   g_return_val_if_fail (g_date_valid (d), 0);
1390   g_return_val_if_fail (slen > 0, 0);
1391   g_return_val_if_fail (format != 0, 0);
1392   g_return_val_if_fail (s != 0, 0);
1393
1394   g_date_to_struct_tm (d, &tm);
1395
1396   locale_format = g_locale_from_utf8 (format, -1, NULL, &locale_format_len, &error);
1397
1398   if (error)
1399     {
1400       g_warning (G_STRLOC "Error converting format to locale encoding: %s\n", error->message);
1401       g_error_free (error);
1402
1403       s[0] = '\0';
1404       return 0;
1405     }
1406
1407   tmpbufsize = MAX (128, locale_format_len * 2);
1408   while (TRUE)
1409     {
1410       tmpbuf = g_malloc (tmpbufsize);
1411
1412       /* Set the first byte to something other than '\0', to be able to
1413        * recognize whether strftime actually failed or just returned "".
1414        */
1415       tmpbuf[0] = '\1';
1416       tmplen = strftime (tmpbuf, tmpbufsize, locale_format, &tm);
1417
1418       if (tmplen == 0 && tmpbuf[0] != '\0')
1419         {
1420           g_free (tmpbuf);
1421           tmpbufsize *= 2;
1422
1423           if (tmpbufsize > 65536)
1424             {
1425               g_warning (G_STRLOC "Maximum buffer size for g_date_strftime exceeded: giving up\n");
1426               g_free (locale_format);
1427
1428               s[0] = '\0';
1429               return 0;
1430             }
1431         }
1432       else
1433         break;
1434     }
1435   g_free (locale_format);
1436
1437   convbuf = g_locale_to_utf8 (tmpbuf, tmplen, NULL, &convlen, &error);
1438   g_free (tmpbuf);
1439
1440   if (error)
1441     {
1442       g_warning (G_STRLOC "Error converting results of strftime to UTF-8: %s\n", error->message);
1443       g_error_free (error);
1444
1445       s[0] = '\0';
1446       return 0;
1447     }
1448
1449   if (slen <= convlen)
1450     {
1451       /* Ensure only whole characters are copied into the buffer.
1452        */
1453       gchar *end = g_utf8_find_prev_char (convbuf, convbuf + slen);
1454       g_assert (end != NULL);
1455       convlen = end - convbuf;
1456
1457       /* Return 0 because the buffer isn't large enough.
1458        */
1459       retval = 0;
1460     }
1461   else
1462     retval = convlen;
1463
1464   memcpy (s, convbuf, convlen);
1465   s[convlen] = '\0';
1466   g_free (convbuf);
1467
1468   return retval;
1469 }
1470
1471 #define __G_DATE_C__
1472 #include "galiasdef.c"
1473