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