gnu/usr.bin/rcs/lib/partime.c

   1 /*      $NetBSD: partime.c,v 1.1.1.2 1996/10/13 21:57:06 veego Exp $    */
   2
   3 /* Parse a string, yielding a struct partime that describes it.  */
   4
   5 /* Copyright 1993, 1994, 1995 Paul Eggert
   6    Distributed under license by the Free Software Foundation, Inc.
   7
   8 This file is part of RCS.
   9
  10 RCS is free software; you can redistribute it and/or modify
  11 it under the terms of the GNU General Public License as published by
  12 the Free Software Foundation; either version 2, or (at your option)
  13 any later version.
  14
  15 RCS is distributed in the hope that it will be useful,
  16 but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 GNU General Public License for more details.
  19
  20 You should have received a copy of the GNU General Public License
  21 along with RCS; see the file COPYING.
  22 If not, write to the Free Software Foundation,
  23 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  24
  25 Report problems and direct all questions to:
  26
  27     rcs-bugs@cs.purdue.edu
  28
  29 */
  30
  31 #if has_conf_h
  32 #       include "conf.h"
  33 #else
  34 #       ifdef __STDC__
  35 #               define P(x) x
  36 #       else
  37 #               define const
  38 #               define P(x) ()
  39 #       endif
  40 #       include <limits.h>
  41 #       include <time.h>
  42 #endif
  43
  44 #include <ctype.h>
  45 #undef isdigit
  46 #define isdigit(c) (((unsigned)(c)-'0') <= 9) /* faster than stock */
  47
  48 #include "partime.h"
  49
  50 char const partimeId[]
  51   = "Id: partime.c,v 5.13 1995/06/16 06:19:24 eggert Exp";
  52
  53
  54 /* Lookup tables for names of months, weekdays, time zones.  */
  55
  56 #define NAME_LENGTH_MAXIMUM 4
  57
  58 struct name_val {
  59         char name[NAME_LENGTH_MAXIMUM];
  60         int val;
  61 };
  62
  63
  64 static char const *parse_decimal P((char const*,int,int,int,int,int*,int*));
  65 static char const *parse_fixed P((char const*,int,int*));
  66 static char const *parse_pattern_letter P((char const*,int,struct partime*));
  67 static char const *parse_prefix P((char const*,struct partime*,int*));
  68 static char const *parse_ranged P((char const*,int,int,int,int*));
  69 static int lookup P((char const*,struct name_val const[]));
  70 static int merge_partime P((struct partime*, struct partime const*));
  71 static void undefine P((struct partime*));
  72
  73
  74 static struct name_val const month_names[] = {
  75         {"jan",0}, {"feb",1}, {"mar",2}, {"apr",3}, {"may",4}, {"jun",5},
  76         {"jul",6}, {"aug",7}, {"sep",8}, {"oct",9}, {"nov",10}, {"dec",11},
  77         {"", TM_UNDEFINED}
  78 };
  79
  80 static struct name_val const weekday_names[] = {
  81         {"sun",0}, {"mon",1}, {"tue",2}, {"wed",3}, {"thu",4}, {"fri",5}, {"sat",6},
  82         {"", TM_UNDEFINED}
  83 };
  84
  85 #define hr60nonnegative(t)  ((t)/100 * 60  +  (t)%100)
  86 #define hr60(t)  ((t)<0 ? -hr60nonnegative(-(t)) : hr60nonnegative(t))
  87 #define zs(t,s)  {s, hr60(t)}
  88 #define zd(t,s,d)  zs(t, s),  zs((t)+100, d)
  89
  90 static struct name_val const zone_names[] = {
  91         zs(-1000, "hst"),               /* Hawaii */
  92         zd(-1000,"hast","hadt"),/* Hawaii-Aleutian */
  93         zd(- 900,"akst","akdt"),/* Alaska */
  94         zd(- 800, "pst", "pdt"),/* Pacific */
  95         zd(- 700, "mst", "mdt"),/* Mountain */
  96         zd(- 600, "cst", "cdt"),/* Central */
  97         zd(- 500, "est", "edt"),/* Eastern */
  98         zd(- 400, "ast", "adt"),/* Atlantic */
  99         zd(- 330, "nst", "ndt"),/* Newfoundland */
 100         zs(  000, "utc"),               /* Coordinated Universal */
 101         zs(  000, "cut"),               /* " */
 102         zs(  000,  "ut"),               /* Universal */
 103         zs(  000,   "z"),               /* Zulu (required by ISO 8601) */
 104         zd(  000, "gmt", "bst"),/* Greenwich Mean, British Summer */
 105         zs(  000, "wet"),               /* Western Europe */
 106         zs(  100, "met"),               /* Middle Europe */
 107         zs(  100, "cet"),               /* Central Europe */
 108         zs(  200, "eet"),               /* Eastern Europe */
 109         zs(  530, "ist"),               /* India */
 110         zd(  900, "jst", "jdt"),/* Japan */
 111         zd(  900, "kst", "kdt"),/* Korea */
 112         zd( 1200,"nzst","nzdt"),/* New Zealand */
 113         { "lt", 1 },
 114 #if 0
 115         /* The following names are duplicates or are not well attested.  */
 116         zs(-1100, "sst"),               /* Samoa */
 117         zs(-1000, "tht"),               /* Tahiti */
 118         zs(- 930, "mqt"),               /* Marquesas */
 119         zs(- 900, "gbt"),               /* Gambier */
 120         zd(- 900, "yst", "ydt"),/* Yukon - name is no longer used */
 121         zs(- 830, "pit"),               /* Pitcairn */
 122         zd(- 500, "cst", "cdt"),/* Cuba */
 123         zd(- 500, "ast", "adt"),/* Acre */
 124         zd(- 400, "wst", "wdt"),/* Western Brazil */
 125         zd(- 400, "ast", "adt"),/* Andes */
 126         zd(- 400, "cst", "cdt"),/* Chile */
 127         zs(- 300, "wgt"),               /* Western Greenland */
 128         zd(- 300, "est", "edt"),/* Eastern South America */
 129         zs(- 300, "mgt"),               /* Middle Greenland */
 130         zd(- 200, "fst", "fdt"),/* Fernando de Noronha */
 131         zs(- 100, "egt"),               /* Eastern Greenland */
 132         zs(- 100, "aat"),               /* Atlantic Africa */
 133         zs(- 100, "act"),               /* Azores and Canaries */
 134         zs(  000, "wat"),               /* West Africa */
 135         zs(  100, "cat"),               /* Central Africa */
 136         zd(  100, "mez","mesz"),/* Mittel-Europaeische Zeit */
 137         zs(  200, "sat"),               /* South Africa */
 138         zd(  200, "ist", "idt"),/* Israel */
 139         zs(  300, "eat"),               /* East Africa */
 140         zd(  300, "ast", "adt"),/* Arabia */
 141         zd(  300, "msk", "msd"),/* Moscow */
 142         zd(  330, "ist", "idt"),/* Iran */
 143         zs(  400, "gst"),               /* Gulf */
 144         zs(  400, "smt"),               /* Seychelles & Mascarene */
 145         zd(  400, "esk", "esd"),/* Yekaterinburg */
 146         zd(  400, "bsk", "bsd"),/* Baku */
 147         zs(  430, "aft"),               /* Afghanistan */
 148         zd(  500, "osk", "osd"),/* Omsk */
 149         zs(  500, "pkt"),               /* Pakistan */
 150         zd(  500, "tsk", "tsd"),/* Tashkent */
 151         zs(  545, "npt"),               /* Nepal */
 152         zs(  600, "bgt"),               /* Bangladesh */
 153         zd(  600, "nsk", "nsd"),/* Novosibirsk */
 154         zs(  630, "bmt"),               /* Burma */
 155         zs(  630, "cct"),               /* Cocos */
 156         zs(  700, "ict"),               /* Indochina */
 157         zs(  700, "jvt"),               /* Java */
 158         zd(  700, "isk", "isd"),/* Irkutsk */
 159         zs(  800, "hkt"),               /* Hong Kong */
 160         zs(  800, "pst"),               /* Philippines */
 161         zs(  800, "sgt"),               /* Singapore */
 162         zd(  800, "cst", "cdt"),/* China */
 163         zd(  800, "ust", "udt"),/* Ulan Bator */
 164         zd(  800, "wst", "wst"),/* Western Australia */
 165         zd(  800, "ysk", "ysd"),/* Yakutsk */
 166         zs(  900, "blt"),               /* Belau */
 167         zs(  900, "mlt"),               /* Moluccas */
 168         zd(  900, "vsk", "vsd"),/* Vladivostok */
 169         zd(  930, "cst", "cst"),/* Central Australia */
 170         zs( 1000, "gst"),               /* Guam */
 171         zd( 1000, "gsk", "gsd"),/* Magadan */
 172         zd( 1000, "est", "est"),/* Eastern Australia */
 173         zd( 1100,"lhst","lhst"),/* Lord Howe */
 174         zd( 1100, "psk", "psd"),/* Petropavlovsk-Kamchatski */
 175         zs( 1100,"ncst"),               /* New Caledonia */
 176         zs( 1130,"nrft"),               /* Norfolk */
 177         zd( 1200, "ask", "asd"),/* Anadyr */
 178         zs( 1245,"nz-chat"),    /* Chatham */
 179         zs( 1300, "tgt"),               /* Tongatapu */
 180 #endif
 181         {"", -1}
 182 };
 183
 184         static int
 185 lookup (s, table)
 186         char const *s;
 187         struct name_val const table[];
 188 /* Look for a prefix of S in TABLE, returning val for first matching entry.  */
 189 {
 190         int j;
 191         char buf[NAME_LENGTH_MAXIMUM];
 192
 193         for (j = 0;  j < NAME_LENGTH_MAXIMUM;  j++) {
 194                 unsigned char c = *s++;
 195                 buf[j] = isupper (c) ? tolower (c) : c;
 196                 if (!isalpha (c))
 197                         break;
 198         }
 199         for (;  table[0].name[0];  table++)
 200                 for (j = 0;  buf[j] == table[0].name[j];  )
 201                         if (++j == NAME_LENGTH_MAXIMUM  ||  !table[0].name[j])
 202                                 goto done;
 203   done:
 204         return table[0].val;
 205 }
 206
 207
 208         static void
 209 undefine (t) struct partime *t;
 210 /* Set *T to ``undefined'' values.  */
 211 {
 212         t->tm.tm_sec = t->tm.tm_min = t->tm.tm_hour = t->tm.tm_mday = t->tm.tm_mon
 213                 = t->tm.tm_year = t->tm.tm_wday = t->tm.tm_yday
 214                 = t->ymodulus = t->yweek
 215                 = TM_UNDEFINED;
 216         t->zone = TM_UNDEFINED_ZONE;
 217 }
 218
 219 /*
 220 * Array of patterns to look for in a date string.
 221 * Order is important: we look for the first matching pattern
 222 * whose values do not contradict values that we already know about.
 223 * See `parse_pattern_letter' below for the meaning of the pattern codes.
 224 */
 225 static char const * const patterns[] = {
 226         /*
 227         * These traditional patterns must come first,
 228         * to prevent an ISO 8601 format from misinterpreting their prefixes.
 229         */
 230         "E_n_y", "x", /* RFC 822 */
 231         "E_n", "n_E", "n", "t:m:s_A", "t:m_A", "t_A", /* traditional */
 232         "y/N/D$", /* traditional RCS */
 233
 234         /* ISO 8601:1988 formats, generalized a bit.  */
 235         "y-N-D$", "4ND$", "Y-N$",
 236         "RND$", "-R=N$", "-R$", "--N=D$", "N=DT",
 237         "--N$", "---D$", "DT",
 238         "Y-d$", "4d$", "R=d$", "-d$", "dT",
 239         "y-W-X", "yWX", "y=W",
 240         "-r-W-X", "r-W-XT", "-rWX", "rWXT", "-W=X", "W=XT", "-W",
 241         "-w-X", "w-XT", "---X$", "XT", "4$",
 242         "T",
 243         "h:m:s$", "hms$", "h:m$", "hm$", "h$", "-m:s$", "-ms$", "-m$", "--s$",
 244         "Y", "Z",
 245
 246         0
 247 };
 248
 249         static char const *
 250 parse_prefix (str, t, pi) char const *str; struct partime *t; int *pi;
 251 /*
 252 * Parse an initial prefix of STR, setting *T accordingly.
 253 * Return the first character after the prefix, or 0 if it couldn't be parsed.
 254 * Start with pattern *PI; if success, set *PI to the next pattern to try.
 255 * Set *PI to -1 if we know there are no more patterns to try;
 256 * if *PI is initially negative, give up immediately.
 257 */
 258 {
 259         int i = *pi;
 260         char const *pat;
 261         unsigned char c;
 262
 263         if (i < 0)
 264                 return 0;
 265
 266         /* Remove initial noise.  */
 267         while (!isalnum (c = *str)  &&  c != '-'  &&  c != '+') {
 268                 if (!c) {
 269                         undefine (t);
 270                         *pi = -1;
 271                         return str;
 272                 }
 273                 str++;
 274         }
 275
 276         /* Try a pattern until one succeeds.  */
 277         while ((pat = patterns[i++]) != 0) {
 278                 char const *s = str;
 279                 undefine (t);
 280                 do {
 281                         if (!(c = *pat++)) {
 282                                 *pi = i;
 283                                 return s;
 284                         }
 285                 } while ((s = parse_pattern_letter (s, c, t)) != 0);
 286         }
 287
 288         return 0;
 289 }
 290
 291         static char const *
 292 parse_fixed (s, digits, res) char const *s; int digits, *res;
 293 /*
 294 * Parse an initial prefix of S of length DIGITS; it must be a number.
 295 * Store the parsed number into *RES.
 296 * Return the first character after the prefix, or 0 if it couldn't be parsed.
 297 */
 298 {
 299         int n = 0;
 300         char const *lim = s + digits;
 301         while (s < lim) {
 302                 unsigned d = *s++ - '0';
 303                 if (9 < d)
 304                         return 0;
 305                 n = 10*n + d;
 306         }
 307         *res = n;
 308         return s;
 309 }
 310
 311         static char const *
 312 parse_ranged (s, digits, lo, hi, res) char const *s; int digits, lo, hi, *res;
 313 /*
 314 * Parse an initial prefix of S of length DIGITS;
 315 * it must be a number in the range LO through HI.
 316 * Store the parsed number into *RES.
 317 * Return the first character after the prefix, or 0 if it couldn't be parsed.
 318 */
 319 {
 320         s = parse_fixed (s, digits, res);
 321         return  s && lo<=*res && *res<=hi  ?  s  :  0;
 322 }
 323
 324         static char const *
 325 parse_decimal (s, digits, lo, hi, resolution, res, fres)
 326         char const *s;
 327         int digits, lo, hi, resolution, *res, *fres;
 328 /*
 329 * Parse an initial prefix of S of length DIGITS;
 330 * it must be a number in the range LO through HI
 331 * and it may be followed by a fraction that is to be computed using RESOLUTION.
 332 * Store the parsed number into *RES; store the fraction times RESOLUTION,
 333 * rounded to the nearest integer, into *FRES.
 334 * Return the first character after the prefix, or 0 if it couldn't be parsed.
 335 */
 336 {
 337         s = parse_fixed (s, digits, res);
 338         if (s && lo<=*res && *res<=hi) {
 339                 int f = 0;
 340                 if ((s[0]==',' || s[0]=='.')  &&  isdigit ((unsigned char) s[1])) {
 341                         char const *s1 = ++s;
 342                         int num10 = 0, denom10 = 10, product;
 343                         while (isdigit ((unsigned char) *++s))
 344                                 denom10 *= 10;
 345                         s = parse_fixed (s1, s - s1, &num10);
 346                         product = num10*resolution;
 347                         f = (product + (denom10>>1)) / denom10;
 348                         f -= f & (product%denom10 == denom10>>1); /* round to even */
 349                         if (f < 0  ||  product/resolution != num10)
 350                                 return 0; /* overflow */
 351                 }
 352                 *fres = f;
 353                 return s;
 354         }
 355         return 0;
 356 }
 357
 358         char *
 359 parzone (s, zone) char const *s; long *zone;
 360 /*
 361 * Parse an initial prefix of S; it must denote a time zone.
 362 * Set *ZONE to the number of seconds east of GMT,
 363 * or to TM_LOCAL_ZONE if it is the local time zone.
 364 * Return the first character after the prefix, or 0 if it couldn't be parsed.
 365 */
 366 {
 367         char sign;
 368         int hh, mm, ss;
 369         int minutesEastOfUTC;
 370         long offset, z;
 371
 372         /*
 373         * The formats are LT, n, n DST, nDST, no, o
 374         * where n is a time zone name
 375         * and o is a time zone offset of the form [-+]hh[:mm[:ss]].
 376         */
 377         switch (*s) {
 378                 case '-': case '+':
 379                         z = 0;
 380                         break;
 381
 382                 default:
 383                         minutesEastOfUTC = lookup (s, zone_names);
 384                         if (minutesEastOfUTC == -1)
 385                                 return 0;
 386
 387                         /* Don't bother to check rest of spelling.  */
 388                         while (isalpha ((unsigned char) *s))
 389                                 s++;
 390
 391                         /* Don't modify LT.  */
 392                         if (minutesEastOfUTC == 1) {
 393                                 *zone = TM_LOCAL_ZONE;
 394                                 return (char *) s;
 395                         }
 396
 397                         z = minutesEastOfUTC * 60L;
 398
 399                         /* Look for trailing " DST".  */
 400                         if (
 401                                 (s[-1]=='T' || s[-1]=='t') &&
 402                                 (s[-2]=='S' || s[-2]=='s') &&
 403                                 (s[-3]=='D' || s[-3]=='t')
 404                         )
 405                                 goto trailing_dst;
 406                         while (isspace ((unsigned char) *s))
 407                                 s++;
 408                         if (
 409                                 (s[0]=='D' || s[0]=='d') &&
 410                                 (s[1]=='S' || s[1]=='s') &&
 411                                 (s[2]=='T' || s[2]=='t')
 412                         ) {
 413                                 s += 3;
 414                           trailing_dst:
 415                                 *zone = z + 60*60;
 416                                 return (char *) s;
 417                         }
 418
 419                         switch (*s) {
 420                                 case '-': case '+': break;
 421                                 default: return (char *) s;
 422                         }
 423         }
 424         sign = *s++;
 425
 426         if (!(s = parse_ranged (s, 2, 0, 23, &hh)))
 427                 return 0;
 428         mm = ss = 0;
 429         if (*s == ':')
 430                 s++;
 431         if (isdigit ((unsigned char) *s)) {
 432                 if (!(s = parse_ranged (s, 2, 0, 59, &mm)))
 433                         return 0;
 434                 if (*s==':' && s[-3]==':' && isdigit ((unsigned char) s[1])) {
 435                         if (!(s = parse_ranged (s + 1, 2, 0, 59, &ss)))
 436                                 return 0;
 437                 }
 438         }
 439         if (isdigit ((unsigned char) *s))
 440                 return 0;
 441         offset = (hh*60 + mm)*60L + ss;
 442         *zone = z + (sign=='-' ? -offset : offset);
 443         /*
 444         * ?? Are fractions allowed here?
 445         * If so, they're not implemented.
 446         */
 447         return (char *) s;
 448 }
 449
 450         static char const *
 451 parse_pattern_letter (s, c, t) char const *s; int c; struct partime *t;
 452 /*
 453 * Parse an initial prefix of S, matching the pattern whose code is C.
 454 * Set *T accordingly.
 455 * Return the first character after the prefix, or 0 if it couldn't be parsed.
 456 */
 457 {
 458         switch (c) {
 459                 case '$': /* The next character must be a non-digit.  */
 460                         if (isdigit ((unsigned char) *s))
 461                                 return 0;
 462                         break;
 463
 464                 case '-': case '/': case ':':
 465                         /* These characters stand for themselves.  */
 466                         if (*s++ != c)
 467                                 return 0;
 468                         break;
 469
 470                 case '4': /* 4-digit year */
 471                         s = parse_fixed (s, 4, &t->tm.tm_year);
 472                         break;
 473
 474                 case '=': /* optional '-' */
 475                         s  +=  *s == '-';
 476                         break;
 477
 478                 case 'A': /* AM or PM */
 479                         /*
 480                         * This matches the regular expression [AaPp][Mm]?.
 481                         * It must not be followed by a letter or digit;
 482                         * otherwise it would match prefixes of strings like "PST".
 483                         */
 484                         switch (*s++) {
 485                                 case 'A': case 'a':
 486                                         if (t->tm.tm_hour == 12)
 487                                                 t->tm.tm_hour = 0;
 488                                         break;
 489
 490                                 case 'P': case 'p':
 491                                         if (t->tm.tm_hour != 12)
 492                                                 t->tm.tm_hour += 12;
 493                                         break;
 494
 495                                 default: return 0;
 496                         }
 497                         switch (*s) {
 498                                 case 'M': case 'm': s++; break;
 499                         }
 500                         if (isalnum (*s))
 501                                 return 0;
 502                         break;
 503
 504                 case 'D': /* day of month [01-31] */
 505                         s = parse_ranged (s, 2, 1, 31, &t->tm.tm_mday);
 506                         break;
 507
 508                 case 'd': /* day of year [001-366] */
 509                         s = parse_ranged (s, 3, 1, 366, &t->tm.tm_yday);
 510                         t->tm.tm_yday--;
 511                         break;
 512
 513                 case 'E': /* extended day of month [1-9, 01-31] */
 514                         s = parse_ranged (s, (
 515                                 isdigit ((unsigned char) s[0]) &&
 516                                 isdigit ((unsigned char) s[1])
 517                         ) + 1, 1, 31, &t->tm.tm_mday);
 518                         break;
 519
 520                 case 'h': /* hour [00-23 followed by optional fraction] */
 521                         {
 522                                 int frac;
 523                                 s = parse_decimal (s, 2, 0, 23, 60*60, &t->tm.tm_hour, &frac);
 524                                 t->tm.tm_min = frac / 60;
 525                                 t->tm.tm_sec = frac % 60;
 526                         }
 527                         break;
 528
 529                 case 'm': /* minute [00-59 followed by optional fraction] */
 530                         s = parse_decimal (s, 2, 0, 59, 60, &t->tm.tm_min, &t->tm.tm_sec);
 531                         break;
 532
 533                 case 'n': /* month name [e.g. "Jan"] */
 534                         if (!TM_DEFINED (t->tm.tm_mon = lookup (s, month_names)))
 535                                 return 0;
 536                         /* Don't bother to check rest of spelling.  */
 537                         while (isalpha ((unsigned char) *s))
 538                                 s++;
 539                         break;
 540
 541                 case 'N': /* month [01-12] */
 542                         s = parse_ranged (s, 2, 1, 12, &t->tm.tm_mon);
 543                         t->tm.tm_mon--;
 544                         break;
 545
 546                 case 'r': /* year % 10 (remainder in origin-0 decade) [0-9] */
 547                         s = parse_fixed (s, 1, &t->tm.tm_year);
 548                         t->ymodulus = 10;
 549                         break;
 550
 551                 case_R:
 552                 case 'R': /* year % 100 (remainder in origin-0 century) [00-99] */
 553                         s = parse_fixed (s, 2, &t->tm.tm_year);
 554                         t->ymodulus = 100;
 555                         break;
 556
 557                 case 's': /* second [00-60 followed by optional fraction] */
 558                         {
 559                                 int frac;
 560                                 s = parse_decimal (s, 2, 0, 60, 1, &t->tm.tm_sec, &frac);
 561                                 t->tm.tm_sec += frac;
 562                         }
 563                         break;
 564
 565                 case 'T': /* 'T' or 't' */
 566                         switch (*s++) {
 567                                 case 'T': case 't': break;
 568                                 default: return 0;
 569                         }
 570                         break;
 571
 572                 case 't': /* traditional hour [1-9 or 01-12] */
 573                         s = parse_ranged (s, (
 574                                 isdigit ((unsigned char) s[0]) && isdigit ((unsigned char) s[1])
 575                         ) + 1, 1, 12, &t->tm.tm_hour);
 576                         break;
 577
 578                 case 'w': /* 'W' or 'w' only (stands for current week) */
 579                         switch (*s++) {
 580                                 case 'W': case 'w': break;
 581                                 default: return 0;
 582                         }
 583                         break;
 584
 585                 case 'W': /* 'W' or 'w', followed by a week of year [00-53] */
 586                         switch (*s++) {
 587                                 case 'W': case 'w': break;
 588                                 default: return 0;
 589                         }
 590                         s = parse_ranged (s, 2, 0, 53, &t->yweek);
 591                         break;
 592
 593                 case 'X': /* weekday (1=Mon ... 7=Sun) [1-7] */
 594                         s = parse_ranged (s, 1, 1, 7, &t->tm.tm_wday);
 595                         t->tm.tm_wday--;
 596                         break;
 597
 598                 case 'x': /* weekday name [e.g. "Sun"] */
 599                         if (!TM_DEFINED (t->tm.tm_wday = lookup (s, weekday_names)))
 600                                 return 0;
 601                         /* Don't bother to check rest of spelling.  */
 602                         while (isalpha ((unsigned char) *s))
 603                                 s++;
 604                         break;
 605
 606                 case 'y': /* either R or Y */
 607                         if (
 608                                 isdigit ((unsigned char) s[0]) &&
 609                                 isdigit ((unsigned char) s[1]) &&
 610                                 !isdigit ((unsigned char) s[2])
 611                         )
 612                                 goto case_R;
 613                         /* fall into */
 614                 case 'Y': /* year in full [4 or more digits] */
 615                         {
 616                                 int len = 0;
 617                                 while (isdigit ((unsigned char) s[len]))
 618                                         len++;
 619                                 if (len < 4)
 620                                         return 0;
 621                                 s = parse_fixed (s, len, &t->tm.tm_year);
 622                         }
 623                         break;
 624
 625                 case 'Z': /* time zone */
 626                         s = parzone (s, &t->zone);
 627                         break;
 628
 629                 case '_': /* possibly empty sequence of non-alphanumerics */
 630                         while (!isalnum (*s)  &&  *s)
 631                                 s++;
 632                         break;
 633
 634                 default: /* bad pattern */
 635                         return 0;
 636         }
 637         return s;
 638 }
 639
 640         static int
 641 merge_partime (t, u) struct partime *t; struct partime const *u;
 642 /*
 643 * If there is no conflict, merge into *T the additional information in *U
 644 * and return 0.  Otherwise do nothing and return -1.
 645 */
 646 {
 647 #       define conflict(a,b) ((a) != (b)  &&  TM_DEFINED (a)  &&  TM_DEFINED (b))
 648         if (
 649                 conflict (t->tm.tm_sec, u->tm.tm_sec) ||
 650                 conflict (t->tm.tm_min, u->tm.tm_min) ||
 651                 conflict (t->tm.tm_hour, u->tm.tm_hour) ||
 652                 conflict (t->tm.tm_mday, u->tm.tm_mday) ||
 653                 conflict (t->tm.tm_mon, u->tm.tm_mon) ||
 654                 conflict (t->tm.tm_year, u->tm.tm_year) ||
 655                 conflict (t->tm.tm_wday, u->tm.tm_yday) ||
 656                 conflict (t->ymodulus, u->ymodulus) ||
 657                 conflict (t->yweek, u->yweek) ||
 658                 (
 659                         t->zone != u->zone &&
 660                         t->zone != TM_UNDEFINED_ZONE &&
 661                         u->zone != TM_UNDEFINED_ZONE
 662                 )
 663         )
 664                 return -1;
 665 #       undef conflict
 666 #       define merge_(a,b) if (TM_DEFINED (b)) (a) = (b);
 667         merge_ (t->tm.tm_sec, u->tm.tm_sec)
 668         merge_ (t->tm.tm_min, u->tm.tm_min)
 669         merge_ (t->tm.tm_hour, u->tm.tm_hour)
 670         merge_ (t->tm.tm_mday, u->tm.tm_mday)
 671         merge_ (t->tm.tm_mon, u->tm.tm_mon)
 672         merge_ (t->tm.tm_year, u->tm.tm_year)
 673         merge_ (t->tm.tm_wday, u->tm.tm_yday)
 674         merge_ (t->ymodulus, u->ymodulus)
 675         merge_ (t->yweek, u->yweek)
 676 #       undef merge_
 677         if (u->zone != TM_UNDEFINED_ZONE) t->zone = u->zone;
 678         return 0;
 679 }
 680
 681         char *
 682 partime (s, t) char const *s; struct partime *t;
 683 /*
 684 * Parse a date/time prefix of S, putting the parsed result into *T.
 685 * Return the first character after the prefix.
 686 * The prefix may contain no useful information;
 687 * in that case, *T will contain only undefined values.
 688 */
 689 {
 690         struct partime p;
 691
 692         undefine (t);
 693         while (*s) {
 694                 int i = 0;
 695                 char const *s1;
 696                 do {
 697                         if (!(s1 = parse_prefix (s, &p, &i)))
 698                                 return (char *) s;
 699                 } while (merge_partime (t, &p) != 0);
 700                 s = s1;
 701         }
 702         return (char *) s;
 703 }