source/modules/getdate.y

   1 %{
   2 /* Parse a string into an internal time stamp.
   3    Copyright (C) 1999, 2000, 2002 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19 /* Originally written by Steven M. Bellovin <smb@research.att.com> while
  20    at the University of North Carolina at Chapel Hill.  Later tweaked by
  21    a couple of people on Usenet.  Completely overhauled by Rich $alz
  22    <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990.
  23
  24    Modified by Paul Eggert <eggert@twinsun.com> in August 1999 to do
  25    the right thing about local DST.  Unlike previous versions, this
  26    version is reentrant.  */
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include <config.h>
  30 # ifdef HAVE_ALLOCA_H
  31 #  include <alloca.h>
  32 # endif
  33 #endif
  34
  35 /* Since the code of getdate.y is not included in the Emacs executable
  36    itself, there is no need to #define static in this file.  Even if
  37    the code were included in the Emacs executable, it probably
  38    wouldn't do any harm to #undef it here; this will only cause
  39    problems if we try to write to a static variable, which I don't
  40    think this code needs to do.  */
  41 #ifdef emacs
  42 # undef static
  43 #endif
  44
  45 #include <ctype.h>
  46
  47 #if HAVE_STDLIB_H
  48 # include <stdlib.h> /* for `free'; used by Bison 1.27 */
  49 #endif
  50
  51 #if STDC_HEADERS || (! defined isascii && ! HAVE_ISASCII)
  52 # define IN_CTYPE_DOMAIN(c) 1
  53 #else
  54 # define IN_CTYPE_DOMAIN(c) isascii (c)
  55 #endif
  56
  57 #define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
  58 #define ISALPHA(c) (IN_CTYPE_DOMAIN (c) && isalpha (c))
  59 #define ISLOWER(c) (IN_CTYPE_DOMAIN (c) && islower (c))
  60 #define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
  61
  62 /* ISDIGIT differs from ISDIGIT_LOCALE, as follows:
  63    - Its arg may be any int or unsigned int; it need not be an unsigned char.
  64    - It's guaranteed to evaluate its argument exactly once.
  65    - It's typically faster.
  66    POSIX says that only '0' through '9' are digits.  Prefer ISDIGIT to
  67    ISDIGIT_LOCALE unless it's important to use the locale's definition
  68    of `digit' even when the host does not conform to POSIX.  */
  69 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
  70
  71 #if STDC_HEADERS || HAVE_STRING_H
  72 # include <string.h>
  73 #endif
  74
  75 #if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8) || __STRICT_ANSI__
  76 # define __attribute__(x)
  77 #endif
  78
  79 #ifndef ATTRIBUTE_UNUSED
  80 # define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
  81 #endif
  82
  83 #define EPOCH_YEAR 1970
  84 #define TM_YEAR_BASE 1900
  85
  86 #define HOUR(x) ((x) * 60)
  87
  88 /* An integer value, and the number of digits in its textual
  89    representation.  */
  90 typedef struct
  91 {
  92   int value;
  93   int digits;
  94 } textint;
  95
  96 /* An entry in the lexical lookup table.  */
  97 typedef struct
  98 {
  99   char const *name;
 100   int type;
 101   int value;
 102 } table;
 103
 104 /* Meridian: am, pm, or 24-hour style.  */
 105 enum { MERam, MERpm, MER24 };
 106
 107 /* Information passed to and from the parser.  */
 108 typedef struct
 109 {
 110   /* The input string remaining to be parsed. */
 111   const char *input;
 112
 113   /* N, if this is the Nth Tuesday.  */
 114   int day_ordinal;
 115
 116   /* Day of week; Sunday is 0.  */
 117   int day_number;
 118
 119   /* tm_isdst flag for the local zone.  */
 120   int local_isdst;
 121
 122   /* Time zone, in minutes east of UTC.  */
 123   int time_zone;
 124
 125   /* Style used for time.  */
 126   int meridian;
 127
 128   /* Gregorian year, month, day, hour, minutes, and seconds.  */
 129   textint year;
 130   int month;
 131   int day;
 132   int hour;
 133   int minutes;
 134   int seconds;
 135
 136   /* Relative year, month, day, hour, minutes, and seconds.  */
 137   int rel_year;
 138   int rel_month;
 139   int rel_day;
 140   int rel_hour;
 141   int rel_minutes;
 142   int rel_seconds;
 143
 144   /* Counts of nonterminals of various flavors parsed so far.  */
 145   int dates_seen;
 146   int days_seen;
 147   int local_zones_seen;
 148   int rels_seen;
 149   int times_seen;
 150   int zones_seen;
 151
 152   /* Table of local time zone abbrevations, terminated by a null entry.  */
 153   table local_time_zone_table[3];
 154 } parser_control;
 155
 156 #define PC (* (parser_control *) parm)
 157 #define YYLEX_PARAM parm
 158 #define YYPARSE_PARAM parm
 159
 160 static int yyerror ();
 161 static int yylex ();
 162
 163 %}
 164
 165 /* We want a reentrant parser.  */
 166 %pure_parser
 167
 168 /* This grammar has 13 shift/reduce conflicts. */
 169 %expect 13
 170
 171 %union
 172 {
 173   int intval;
 174   textint textintval;
 175 }
 176
 177 %token tAGO tDST
 178
 179 %token <intval> tDAY tDAY_UNIT tDAYZONE tHOUR_UNIT tLOCAL_ZONE tMERIDIAN
 180 %token <intval> tMINUTE_UNIT tMONTH tMONTH_UNIT tSEC_UNIT tYEAR_UNIT tZONE
 181
 182 %token <textintval> tSNUMBER tUNUMBER
 183
 184 %type <intval> o_merid
 185
 186 %%
 187
 188 spec:
 189     /* empty */
 190   | spec item
 191   ;
 192
 193 item:
 194     time
 195       { PC.times_seen++; }
 196   | local_zone
 197       { PC.local_zones_seen++; }
 198   | zone
 199       { PC.zones_seen++; }
 200   | date
 201       { PC.dates_seen++; }
 202   | day
 203       { PC.days_seen++; }
 204   | rel
 205       { PC.rels_seen++; }
 206   | number
 207   ;
 208
 209 time:
 210     tUNUMBER tMERIDIAN
 211       {
 212         PC.hour = $1.value;
 213         PC.minutes = 0;
 214         PC.seconds = 0;
 215         PC.meridian = $2;
 216       }
 217   | tUNUMBER ':' tUNUMBER o_merid
 218       {
 219         PC.hour = $1.value;
 220         PC.minutes = $3.value;
 221         PC.seconds = 0;
 222         PC.meridian = $4;
 223       }
 224   | tUNUMBER ':' tUNUMBER tSNUMBER
 225       {
 226         PC.hour = $1.value;
 227         PC.minutes = $3.value;
 228         PC.meridian = MER24;
 229         PC.zones_seen++;
 230         PC.time_zone = $4.value % 100 + ($4.value / 100) * 60;
 231       }
 232   | tUNUMBER ':' tUNUMBER ':' tUNUMBER o_merid
 233       {
 234         PC.hour = $1.value;
 235         PC.minutes = $3.value;
 236         PC.seconds = $5.value;
 237         PC.meridian = $6;
 238       }
 239   | tUNUMBER ':' tUNUMBER ':' tUNUMBER tSNUMBER
 240       {
 241         PC.hour = $1.value;
 242         PC.minutes = $3.value;
 243         PC.seconds = $5.value;
 244         PC.meridian = MER24;
 245         PC.zones_seen++;
 246         PC.time_zone = $6.value % 100 + ($6.value / 100) * 60;
 247       }
 248   ;
 249
 250 local_zone:
 251     tLOCAL_ZONE
 252       { PC.local_isdst = $1; }
 253   | tLOCAL_ZONE tDST
 254       { PC.local_isdst = $1 < 0 ? 1 : $1 + 1; }
 255   ;
 256
 257 zone:
 258     tZONE
 259       { PC.time_zone = $1; }
 260   | tDAYZONE
 261       { PC.time_zone = $1 + 60; }
 262   | tZONE tDST
 263       { PC.time_zone = $1 + 60; }
 264   ;
 265
 266 day:
 267     tDAY
 268       {
 269         PC.day_ordinal = 1;
 270         PC.day_number = $1;
 271       }
 272   | tDAY ','
 273       {
 274         PC.day_ordinal = 1;
 275         PC.day_number = $1;
 276       }
 277   | tUNUMBER tDAY
 278       {
 279         PC.day_ordinal = $1.value;
 280         PC.day_number = $2;
 281       }
 282   ;
 283
 284 date:
 285     tUNUMBER '/' tUNUMBER
 286       {
 287         PC.month = $1.value;
 288         PC.day = $3.value;
 289       }
 290   | tUNUMBER '/' tUNUMBER '/' tUNUMBER
 291       {
 292         /* Interpret as YYYY/MM/DD if the first value has 4 or more digits,
 293            otherwise as MM/DD/YY.
 294            The goal in recognizing YYYY/MM/DD is solely to support legacy
 295            machine-generated dates like those in an RCS log listing.  If
 296            you want portability, use the ISO 8601 format.  */
 297         if (4 <= $1.digits)
 298           {
 299             PC.year = $1;
 300             PC.month = $3.value;
 301             PC.day = $5.value;
 302           }
 303         else
 304           {
 305             PC.month = $1.value;
 306             PC.day = $3.value;
 307             PC.year = $5;
 308           }
 309       }
 310   | tUNUMBER tSNUMBER tSNUMBER
 311       {
 312         /* ISO 8601 format.  YYYY-MM-DD.  */
 313         PC.year = $1;
 314         PC.month = -$2.value;
 315         PC.day = -$3.value;
 316       }
 317   | tUNUMBER tMONTH tSNUMBER
 318       {
 319         /* e.g. 17-JUN-1992.  */
 320         PC.day = $1.value;
 321         PC.month = $2;
 322         PC.year.value = -$3.value;
 323         PC.year.digits = $3.digits;
 324       }
 325   | tMONTH tUNUMBER
 326       {
 327         PC.month = $1;
 328         PC.day = $2.value;
 329       }
 330   | tMONTH tUNUMBER ',' tUNUMBER
 331       {
 332         PC.month = $1;
 333         PC.day = $2.value;
 334         PC.year = $4;
 335       }
 336   | tUNUMBER tMONTH
 337       {
 338         PC.day = $1.value;
 339         PC.month = $2;
 340       }
 341   | tUNUMBER tMONTH tUNUMBER
 342       {
 343         PC.day = $1.value;
 344         PC.month = $2;
 345         PC.year = $3;
 346       }
 347   ;
 348
 349 rel:
 350     relunit tAGO
 351       {
 352         PC.rel_seconds = -PC.rel_seconds;
 353         PC.rel_minutes = -PC.rel_minutes;
 354         PC.rel_hour = -PC.rel_hour;
 355         PC.rel_day = -PC.rel_day;
 356         PC.rel_month = -PC.rel_month;
 357         PC.rel_year = -PC.rel_year;
 358       }
 359   | relunit
 360   ;
 361
 362 relunit:
 363     tUNUMBER tYEAR_UNIT
 364       { PC.rel_year += $1.value * $2; }
 365   | tSNUMBER tYEAR_UNIT
 366       { PC.rel_year += $1.value * $2; }
 367   | tYEAR_UNIT
 368       { PC.rel_year += $1; }
 369   | tUNUMBER tMONTH_UNIT
 370       { PC.rel_month += $1.value * $2; }
 371   | tSNUMBER tMONTH_UNIT
 372       { PC.rel_month += $1.value * $2; }
 373   | tMONTH_UNIT
 374       { PC.rel_month += $1; }
 375   | tUNUMBER tDAY_UNIT
 376       { PC.rel_day += $1.value * $2; }
 377   | tSNUMBER tDAY_UNIT
 378       { PC.rel_day += $1.value * $2; }
 379   | tDAY_UNIT
 380       { PC.rel_day += $1; }
 381   | tUNUMBER tHOUR_UNIT
 382       { PC.rel_hour += $1.value * $2; }
 383   | tSNUMBER tHOUR_UNIT
 384       { PC.rel_hour += $1.value * $2; }
 385   | tHOUR_UNIT
 386       { PC.rel_hour += $1; }
 387   | tUNUMBER tMINUTE_UNIT
 388       { PC.rel_minutes += $1.value * $2; }
 389   | tSNUMBER tMINUTE_UNIT
 390       { PC.rel_minutes += $1.value * $2; }
 391   | tMINUTE_UNIT
 392       { PC.rel_minutes += $1; }
 393   | tUNUMBER tSEC_UNIT
 394       { PC.rel_seconds += $1.value * $2; }
 395   | tSNUMBER tSEC_UNIT
 396       { PC.rel_seconds += $1.value * $2; }
 397   | tSEC_UNIT
 398       { PC.rel_seconds += $1; }
 399   ;
 400
 401 number:
 402     tUNUMBER
 403       {
 404         if (PC.dates_seen
 405             && ! PC.rels_seen && (PC.times_seen || 2 < $1.digits))
 406           PC.year = $1;
 407         else
 408           {
 409             if (4 < $1.digits)
 410               {
 411                 PC.dates_seen++;
 412                 PC.day = $1.value % 100;
 413                 PC.month = ($1.value / 100) % 100;
 414                 PC.year.value = $1.value / 10000;
 415                 PC.year.digits = $1.digits - 4;
 416               }
 417             else
 418               {
 419                 PC.times_seen++;
 420                 if ($1.digits <= 2)
 421                   {
 422                     PC.hour = $1.value;
 423                     PC.minutes = 0;
 424                   }
 425                 else
 426                   {
 427                     PC.hour = $1.value / 100;
 428                     PC.minutes = $1.value % 100;
 429                   }
 430                 PC.seconds = 0;
 431                 PC.meridian = MER24;
 432               }
 433           }
 434       }
 435   ;
 436
 437 o_merid:
 438     /* empty */
 439       { $$ = MER24; }
 440   | tMERIDIAN
 441       { $$ = $1; }
 442   ;
 443
 444 %%
 445
 446 /* Include this file down here because bison inserts code above which
 447    may define-away `const'.  We want the prototype for get_date to have
 448    the same signature as the function definition.  */
 449 #include "modules/getdate.h"
 450
 451 #ifndef gmtime
 452 struct tm *gmtime ();
 453 #endif
 454 #ifndef localtime
 455 struct tm *localtime ();
 456 #endif
 457 #ifndef mktime
 458 time_t mktime ();
 459 #endif
 460
 461 static table const meridian_table[] =
 462 {
 463   { "AM",   tMERIDIAN, MERam },
 464   { "A.M.", tMERIDIAN, MERam },
 465   { "PM",   tMERIDIAN, MERpm },
 466   { "P.M.", tMERIDIAN, MERpm },
 467   { 0, 0, 0 }
 468 };
 469
 470 static table const dst_table[] =
 471 {
 472   { "DST", tDST, 0 }
 473 };
 474
 475 static table const month_and_day_table[] =
 476 {
 477   { "JANUARY",  tMONTH,  1 },
 478   { "FEBRUARY", tMONTH,  2 },
 479   { "MARCH",    tMONTH,  3 },
 480   { "APRIL",    tMONTH,  4 },
 481   { "MAY",      tMONTH,  5 },
 482   { "JUNE",     tMONTH,  6 },
 483   { "JULY",     tMONTH,  7 },
 484   { "AUGUST",   tMONTH,  8 },
 485   { "SEPTEMBER",tMONTH,  9 },
 486   { "SEPT",     tMONTH,  9 },
 487   { "OCTOBER",  tMONTH, 10 },
 488   { "NOVEMBER", tMONTH, 11 },
 489   { "DECEMBER", tMONTH, 12 },
 490   { "SUNDAY",   tDAY,    0 },
 491   { "MONDAY",   tDAY,    1 },
 492   { "TUESDAY",  tDAY,    2 },
 493   { "TUES",     tDAY,    2 },
 494   { "WEDNESDAY",tDAY,    3 },
 495   { "WEDNES",   tDAY,    3 },
 496   { "THURSDAY", tDAY,    4 },
 497   { "THUR",     tDAY,    4 },
 498   { "THURS",    tDAY,    4 },
 499   { "FRIDAY",   tDAY,    5 },
 500   { "SATURDAY", tDAY,    6 },
 501   { 0, 0, 0 }
 502 };
 503
 504 static table const time_units_table[] =
 505 {
 506   { "YEAR",     tYEAR_UNIT,      1 },
 507   { "MONTH",    tMONTH_UNIT,     1 },
 508   { "FORTNIGHT",tDAY_UNIT,      14 },
 509   { "WEEK",     tDAY_UNIT,       7 },
 510   { "DAY",      tDAY_UNIT,       1 },
 511   { "HOUR",     tHOUR_UNIT,      1 },
 512   { "MINUTE",   tMINUTE_UNIT,    1 },
 513   { "MIN",      tMINUTE_UNIT,    1 },
 514   { "SECOND",   tSEC_UNIT,       1 },
 515   { "SEC",      tSEC_UNIT,       1 },
 516   { 0, 0, 0 }
 517 };
 518
 519 /* Assorted relative-time words. */
 520 static table const relative_time_table[] =
 521 {
 522   { "TOMORROW", tMINUTE_UNIT,   24 * 60 },
 523   { "YESTERDAY",tMINUTE_UNIT,   - (24 * 60) },
 524   { "TODAY",    tMINUTE_UNIT,    0 },
 525   { "NOW",      tMINUTE_UNIT,    0 },
 526   { "LAST",     tUNUMBER,       -1 },
 527   { "THIS",     tUNUMBER,        0 },
 528   { "NEXT",     tUNUMBER,        1 },
 529   { "FIRST",    tUNUMBER,        1 },
 530 /*{ "SECOND",   tUNUMBER,        2 }, */
 531   { "THIRD",    tUNUMBER,        3 },
 532   { "FOURTH",   tUNUMBER,        4 },
 533   { "FIFTH",    tUNUMBER,        5 },
 534   { "SIXTH",    tUNUMBER,        6 },
 535   { "SEVENTH",  tUNUMBER,        7 },
 536   { "EIGHTH",   tUNUMBER,        8 },
 537   { "NINTH",    tUNUMBER,        9 },
 538   { "TENTH",    tUNUMBER,       10 },
 539   { "ELEVENTH", tUNUMBER,       11 },
 540   { "TWELFTH",  tUNUMBER,       12 },
 541   { "AGO",      tAGO,            1 },
 542   { 0, 0, 0 }
 543 };
 544
 545 /* The time zone table.  This table is necessarily incomplete, as time
 546    zone abbreviations are ambiguous; e.g. Australians interpret "EST"
 547    as Eastern time in Australia, not as US Eastern Standard Time.
 548    You cannot rely on getdate to handle arbitrary time zone
 549    abbreviations; use numeric abbreviations like `-0500' instead.  */
 550 static table const time_zone_table[] =
 551 {
 552   { "GMT",      tZONE,     HOUR ( 0) }, /* Greenwich Mean */
 553   { "UT",       tZONE,     HOUR ( 0) }, /* Universal (Coordinated) */
 554   { "UTC",      tZONE,     HOUR ( 0) },
 555   { "WET",      tZONE,     HOUR ( 0) }, /* Western European */
 556   { "WEST",     tDAYZONE,  HOUR ( 0) }, /* Western European Summer */
 557   { "BST",      tDAYZONE,  HOUR ( 0) }, /* British Summer */
 558   { "ART",      tZONE,    -HOUR ( 3) }, /* Argentina */
 559   { "BRT",      tZONE,    -HOUR ( 3) }, /* Brazil */
 560   { "BRST",     tDAYZONE, -HOUR ( 3) }, /* Brazil Summer */
 561   { "NST",      tZONE,   -(HOUR ( 3) + 30) },   /* Newfoundland Standard */
 562   { "NDT",      tDAYZONE,-(HOUR ( 3) + 30) },   /* Newfoundland Daylight */
 563   { "AST",      tZONE,    -HOUR ( 4) }, /* Atlantic Standard */
 564   { "ADT",      tDAYZONE, -HOUR ( 4) }, /* Atlantic Daylight */
 565   { "CLT",      tZONE,    -HOUR ( 4) }, /* Chile */
 566   { "CLST",     tDAYZONE, -HOUR ( 4) }, /* Chile Summer */
 567   { "EST",      tZONE,    -HOUR ( 5) }, /* Eastern Standard */
 568   { "EDT",      tDAYZONE, -HOUR ( 5) }, /* Eastern Daylight */
 569   { "CST",      tZONE,    -HOUR ( 6) }, /* Central Standard */
 570   { "CDT",      tDAYZONE, -HOUR ( 6) }, /* Central Daylight */
 571   { "MST",      tZONE,    -HOUR ( 7) }, /* Mountain Standard */
 572   { "MDT",      tDAYZONE, -HOUR ( 7) }, /* Mountain Daylight */
 573   { "PST",      tZONE,    -HOUR ( 8) }, /* Pacific Standard */
 574   { "PDT",      tDAYZONE, -HOUR ( 8) }, /* Pacific Daylight */
 575   { "AKST",     tZONE,    -HOUR ( 9) }, /* Alaska Standard */
 576   { "AKDT",     tDAYZONE, -HOUR ( 9) }, /* Alaska Daylight */
 577   { "HST",      tZONE,    -HOUR (10) }, /* Hawaii Standard */
 578   { "HAST",     tZONE,    -HOUR (10) }, /* Hawaii-Aleutian Standard */
 579   { "HADT",     tDAYZONE, -HOUR (10) }, /* Hawaii-Aleutian Daylight */
 580   { "SST",      tZONE,    -HOUR (12) }, /* Samoa Standard */
 581   { "WAT",      tZONE,     HOUR ( 1) }, /* West Africa */
 582   { "CET",      tZONE,     HOUR ( 1) }, /* Central European */
 583   { "CEST",     tDAYZONE,  HOUR ( 1) }, /* Central European Summer */
 584   { "MET",      tZONE,     HOUR ( 1) }, /* Middle European */
 585   { "MEZ",      tZONE,     HOUR ( 1) }, /* Middle European */
 586   { "MEST",     tDAYZONE,  HOUR ( 1) }, /* Middle European Summer */
 587   { "MESZ",     tDAYZONE,  HOUR ( 1) }, /* Middle European Summer */
 588   { "EET",      tZONE,     HOUR ( 2) }, /* Eastern European */
 589   { "EEST",     tDAYZONE,  HOUR ( 2) }, /* Eastern European Summer */
 590   { "CAT",      tZONE,     HOUR ( 2) }, /* Central Africa */
 591   { "SAST",     tZONE,     HOUR ( 2) }, /* South Africa Standard */
 592   { "EAT",      tZONE,     HOUR ( 3) }, /* East Africa */
 593   { "MSK",      tZONE,     HOUR ( 3) }, /* Moscow */
 594   { "MSD",      tDAYZONE,  HOUR ( 3) }, /* Moscow Daylight */
 595   { "IST",      tZONE,    (HOUR ( 5) + 30) },   /* India Standard */
 596   { "SGT",      tZONE,     HOUR ( 8) }, /* Singapore */
 597   { "KST",      tZONE,     HOUR ( 9) }, /* Korea Standard */
 598   { "JST",      tZONE,     HOUR ( 9) }, /* Japan Standard */
 599   { "GST",      tZONE,     HOUR (10) }, /* Guam Standard */
 600   { "NZST",     tZONE,     HOUR (12) }, /* New Zealand Standard */
 601   { "NZDT",     tDAYZONE,  HOUR (12) }, /* New Zealand Daylight */
 602   { 0, 0, 0  }
 603 };
 604
 605 /* Military time zone table. */
 606 static table const military_table[] =
 607 {
 608   { "A", tZONE, -HOUR ( 1) },
 609   { "B", tZONE, -HOUR ( 2) },
 610   { "C", tZONE, -HOUR ( 3) },
 611   { "D", tZONE, -HOUR ( 4) },
 612   { "E", tZONE, -HOUR ( 5) },
 613   { "F", tZONE, -HOUR ( 6) },
 614   { "G", tZONE, -HOUR ( 7) },
 615   { "H", tZONE, -HOUR ( 8) },
 616   { "I", tZONE, -HOUR ( 9) },
 617   { "K", tZONE, -HOUR (10) },
 618   { "L", tZONE, -HOUR (11) },
 619   { "M", tZONE, -HOUR (12) },
 620   { "N", tZONE,  HOUR ( 1) },
 621   { "O", tZONE,  HOUR ( 2) },
 622   { "P", tZONE,  HOUR ( 3) },
 623   { "Q", tZONE,  HOUR ( 4) },
 624   { "R", tZONE,  HOUR ( 5) },
 625   { "S", tZONE,  HOUR ( 6) },
 626   { "T", tZONE,  HOUR ( 7) },
 627   { "U", tZONE,  HOUR ( 8) },
 628   { "V", tZONE,  HOUR ( 9) },
 629   { "W", tZONE,  HOUR (10) },
 630   { "X", tZONE,  HOUR (11) },
 631   { "Y", tZONE,  HOUR (12) },
 632   { "Z", tZONE,  HOUR ( 0) },
 633   { 0, 0, 0 }
 634 };
 635
 636 \f
 637
 638 static int
 639 to_hour (int hours, int meridian)
 640 {
 641   switch (meridian)
 642     {
 643     case MER24:
 644       return 0 <= hours && hours < 24 ? hours : -1;
 645     case MERam:
 646       return 0 < hours && hours < 12 ? hours : hours == 12 ? 0 : -1;
 647     case MERpm:
 648       return 0 < hours && hours < 12 ? hours + 12 : hours == 12 ? 12 : -1;
 649     default:
 650       abort ();
 651     }
 652   /* NOTREACHED */
 653     return 0;
 654 }
 655
 656 static int
 657 to_year (textint textyear)
 658 {
 659   int year = textyear.value;
 660
 661   if (year < 0)
 662     year = -year;
 663
 664   /* XPG4 suggests that years 00-68 map to 2000-2068, and
 665      years 69-99 map to 1969-1999.  */
 666   if (textyear.digits == 2)
 667     year += year < 69 ? 2000 : 1900;
 668
 669   return year;
 670 }
 671
 672 static table const *
 673 lookup_zone (parser_control const *pc, char const *name)
 674 {
 675   table const *tp;
 676
 677   /* Try local zone abbreviations first; they're more likely to be right.  */
 678   for (tp = pc->local_time_zone_table; tp->name; tp++)
 679     if (strcmp (name, tp->name) == 0)
 680       return tp;
 681
 682   for (tp = time_zone_table; tp->name; tp++)
 683     if (strcmp (name, tp->name) == 0)
 684       return tp;
 685
 686   return 0;
 687 }
 688
 689 #if ! HAVE_TM_GMTOFF
 690 /* Yield the difference between *A and *B,
 691    measured in seconds, ignoring leap seconds.
 692    The body of this function is taken directly from the GNU C Library;
 693    see src/strftime.c.  */
 694 static int
 695 tm_diff (struct tm const *a, struct tm const *b)
 696 {
 697   /* Compute intervening leap days correctly even if year is negative.
 698      Take care to avoid int overflow in leap day calculations,
 699      but it's OK to assume that A and B are close to each other.  */
 700   int a4 = (a->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (a->tm_year & 3);
 701   int b4 = (b->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (b->tm_year & 3);
 702   int a100 = a4 / 25 - (a4 % 25 < 0);
 703   int b100 = b4 / 25 - (b4 % 25 < 0);
 704   int a400 = a100 >> 2;
 705   int b400 = b100 >> 2;
 706   int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
 707   int years = a->tm_year - b->tm_year;
 708   int days = (365 * years + intervening_leap_days
 709               + (a->tm_yday - b->tm_yday));
 710   return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
 711                 + (a->tm_min - b->tm_min))
 712           + (a->tm_sec - b->tm_sec));
 713 }
 714 #endif /* ! HAVE_TM_GMTOFF */
 715
 716 static table const *
 717 lookup_word (parser_control const *pc, char *word)
 718 {
 719   char *p;
 720   char *q;
 721   size_t wordlen;
 722   table const *tp;
 723   int i;
 724   int abbrev;
 725
 726   /* Make it uppercase.  */
 727   for (p = word; *p; p++)
 728     if (ISLOWER ((unsigned char) *p))
 729       *p = toupper ((unsigned char) *p);
 730
 731   for (tp = meridian_table; tp->name; tp++)
 732     if (strcmp (word, tp->name) == 0)
 733       return tp;
 734
 735   /* See if we have an abbreviation for a month. */
 736   wordlen = strlen (word);
 737   abbrev = wordlen == 3 || (wordlen == 4 && word[3] == '.');
 738
 739   for (tp = month_and_day_table; tp->name; tp++)
 740     if ((abbrev ? strncmp (word, tp->name, 3) : strcmp (word, tp->name)) == 0)
 741       return tp;
 742
 743   if ((tp = lookup_zone (pc, word)))
 744     return tp;
 745
 746   if (strcmp (word, dst_table[0].name) == 0)
 747     return dst_table;
 748
 749   for (tp = time_units_table; tp->name; tp++)
 750     if (strcmp (word, tp->name) == 0)
 751       return tp;
 752
 753   /* Strip off any plural and try the units table again. */
 754   if (word[wordlen - 1] == 'S')
 755     {
 756       word[wordlen - 1] = '\0';
 757       for (tp = time_units_table; tp->name; tp++)
 758         if (strcmp (word, tp->name) == 0)
 759           return tp;
 760       word[wordlen - 1] = 'S';  /* For "this" in relative_time_table.  */
 761     }
 762
 763   for (tp = relative_time_table; tp->name; tp++)
 764     if (strcmp (word, tp->name) == 0)
 765       return tp;
 766
 767   /* Military time zones. */
 768   if (wordlen == 1)
 769     for (tp = military_table; tp->name; tp++)
 770       if (word[0] == tp->name[0])
 771         return tp;
 772
 773   /* Drop out any periods and try the time zone table again. */
 774   for (i = 0, p = q = word; (*p = *q); q++)
 775     if (*q == '.')
 776       i = 1;
 777     else
 778       p++;
 779   if (i && (tp = lookup_zone (pc, word)))
 780     return tp;
 781
 782   return 0;
 783 }
 784
 785 static int
 786 yylex (YYSTYPE *lvalp, parser_control *pc)
 787 {
 788   unsigned char c;
 789   int count;
 790
 791   for (;;)
 792     {
 793       while (c = *pc->input, ISSPACE (c))
 794         pc->input++;
 795
 796       if (ISDIGIT (c) || c == '-' || c == '+')
 797         {
 798           char const *p;
 799           int sign;
 800           int value;
 801           if (c == '-' || c == '+')
 802             {
 803               sign = c == '-' ? -1 : 1;
 804               c = *++pc->input;
 805               if (! ISDIGIT (c))
 806                 /* skip the '-' sign */
 807                 continue;
 808             }
 809           else
 810             sign = 0;
 811           p = pc->input;
 812           value = 0;
 813           do
 814             {
 815               value = 10 * value + c - '0';
 816               c = *++p;
 817             }
 818           while (ISDIGIT (c));
 819           lvalp->textintval.value = sign < 0 ? -value : value;
 820           lvalp->textintval.digits = p - pc->input;
 821           pc->input = p;
 822           return sign ? tSNUMBER : tUNUMBER;
 823         }
 824
 825       if (ISALPHA (c))
 826         {
 827           char buff[20];
 828           char *p = buff;
 829           table const *tp;
 830
 831           do
 832             {
 833               if (p < buff + sizeof buff - 1)
 834                 *p++ = c;
 835               c = *++pc->input;
 836             }
 837           while (ISALPHA (c) || c == '.');
 838
 839           *p = '\0';
 840           tp = lookup_word (pc, buff);
 841           if (! tp)
 842             return '?';
 843           lvalp->intval = tp->value;
 844           return tp->type;
 845         }
 846
 847       if (c != '(')
 848         return *pc->input++;
 849       count = 0;
 850       do
 851         {
 852           c = *pc->input++;
 853           if (c == '\0')
 854             return c;
 855           if (c == '(')
 856             count++;
 857           else if (c == ')')
 858             count--;
 859         }
 860       while (count > 0);
 861     }
 862 }
 863
 864 /* Do nothing if the parser reports an error.  */
 865 static int
 866 yyerror (char *s ATTRIBUTE_UNUSED)
 867 {
 868   return 0;
 869 }
 870
 871 /* Parse a date/time string P.  Return the corresponding time_t value,
 872    or (time_t) -1 if there is an error.  P can be an incomplete or
 873    relative time specification; if so, use *NOW as the basis for the
 874    returned time.  */
 875 time_t
 876 get_date (const char *p, const time_t *now)
 877 {
 878   time_t Start = now ? *now : time (0);
 879   struct tm *tmp = localtime (&Start);
 880   struct tm tm;
 881   struct tm tm0;
 882   parser_control pc;
 883
 884   if (! tmp)
 885     return -1;
 886
 887   pc.input = p;
 888   pc.year.value = tmp->tm_year + TM_YEAR_BASE;
 889   pc.year.digits = 4;
 890   pc.month = tmp->tm_mon + 1;
 891   pc.day = tmp->tm_mday;
 892   pc.hour = tmp->tm_hour;
 893   pc.minutes = tmp->tm_min;
 894   pc.seconds = tmp->tm_sec;
 895   tm.tm_isdst = tmp->tm_isdst;
 896
 897   pc.meridian = MER24;
 898   pc.rel_seconds = 0;
 899   pc.rel_minutes = 0;
 900   pc.rel_hour = 0;
 901   pc.rel_day = 0;
 902   pc.rel_month = 0;
 903   pc.rel_year = 0;
 904   pc.dates_seen = 0;
 905   pc.days_seen = 0;
 906   pc.rels_seen = 0;
 907   pc.times_seen = 0;
 908   pc.local_zones_seen = 0;
 909   pc.zones_seen = 0;
 910
 911 #if HAVE_STRUCT_TM_TM_ZONE
 912   pc.local_time_zone_table[0].name = tmp->tm_zone;
 913   pc.local_time_zone_table[0].type = tLOCAL_ZONE;
 914   pc.local_time_zone_table[0].value = tmp->tm_isdst;
 915   pc.local_time_zone_table[1].name = 0;
 916
 917   /* Probe the names used in the next three calendar quarters, looking
 918      for a tm_isdst different from the one we already have.  */
 919   {
 920     int quarter;
 921     for (quarter = 1; quarter <= 3; quarter++)
 922       {
 923         time_t probe = Start + quarter * (90 * 24 * 60 * 60);
 924         struct tm *probe_tm = localtime (&probe);
 925         if (probe_tm && probe_tm->tm_zone
 926             && probe_tm->tm_isdst != pc.local_time_zone_table[0].value)
 927           {
 928               {
 929                 pc.local_time_zone_table[1].name = probe_tm->tm_zone;
 930                 pc.local_time_zone_table[1].type = tLOCAL_ZONE;
 931                 pc.local_time_zone_table[1].value = probe_tm->tm_isdst;
 932                 pc.local_time_zone_table[2].name = 0;
 933               }
 934             break;
 935           }
 936       }
 937   }
 938 #else
 939 #if HAVE_TZNAME
 940   {
 941 # ifndef tzname
 942     extern char *tzname[];
 943 # endif
 944     int i;
 945     for (i = 0; i < 2; i++)
 946       {
 947         pc.local_time_zone_table[i].name = tzname[i];
 948         pc.local_time_zone_table[i].type = tLOCAL_ZONE;
 949         pc.local_time_zone_table[i].value = i;
 950       }
 951     pc.local_time_zone_table[i].name = 0;
 952   }
 953 #else
 954   pc.local_time_zone_table[0].name = 0;
 955 #endif
 956 #endif
 957
 958   if (pc.local_time_zone_table[0].name && pc.local_time_zone_table[1].name
 959       && ! strcmp (pc.local_time_zone_table[0].name,
 960                    pc.local_time_zone_table[1].name))
 961     {
 962       /* This locale uses the same abbrevation for standard and
 963          daylight times.  So if we see that abbreviation, we don't
 964          know whether it's daylight time.  */
 965       pc.local_time_zone_table[0].value = -1;
 966       pc.local_time_zone_table[1].name = 0;
 967     }
 968
 969   if (yyparse (&pc) != 0
 970       || 1 < pc.times_seen || 1 < pc.dates_seen || 1 < pc.days_seen
 971       || 1 < (pc.local_zones_seen + pc.zones_seen)
 972       || (pc.local_zones_seen && 1 < pc.local_isdst))
 973     return -1;
 974
 975   tm.tm_year = to_year (pc.year) - TM_YEAR_BASE + pc.rel_year;
 976   tm.tm_mon = pc.month - 1 + pc.rel_month;
 977   tm.tm_mday = pc.day + pc.rel_day;
 978   if (pc.times_seen || (pc.rels_seen && ! pc.dates_seen && ! pc.days_seen))
 979     {
 980       tm.tm_hour = to_hour (pc.hour, pc.meridian);
 981       if (tm.tm_hour < 0)
 982         return -1;
 983       tm.tm_min = pc.minutes;
 984       tm.tm_sec = pc.seconds;
 985     }
 986   else
 987     {
 988       tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
 989     }
 990
 991   /* Let mktime deduce tm_isdst if we have an absolute time stamp,
 992      or if the relative time stamp mentions days, months, or years.  */
 993   if (pc.dates_seen | pc.days_seen | pc.times_seen | pc.rel_day
 994       | pc.rel_month | pc.rel_year)
 995     tm.tm_isdst = -1;
 996
 997   /* But if the input explicitly specifies local time with or without
 998      DST, give mktime that information.  */
 999   if (pc.local_zones_seen)
1000     tm.tm_isdst = pc.local_isdst;
1001
1002   tm0 = tm;
1003
1004   Start = mktime (&tm);
1005
1006   if (Start == (time_t) -1)
1007     {
1008
1009       /* Guard against falsely reporting errors near the time_t boundaries
1010          when parsing times in other time zones.  For example, if the min
1011          time_t value is 1970-01-01 00:00:00 UTC and we are 8 hours ahead
1012          of UTC, then the min localtime value is 1970-01-01 08:00:00; if
1013          we apply mktime to 1970-01-01 00:00:00 we will get an error, so
1014          we apply mktime to 1970-01-02 08:00:00 instead and adjust the time
1015          zone by 24 hours to compensate.  This algorithm assumes that
1016          there is no DST transition within a day of the time_t boundaries.  */
1017       if (pc.zones_seen)
1018         {
1019           tm = tm0;
1020           if (tm.tm_year <= EPOCH_YEAR - TM_YEAR_BASE)
1021             {
1022               tm.tm_mday++;
1023               pc.time_zone += 24 * 60;
1024             }
1025           else
1026             {
1027               tm.tm_mday--;
1028               pc.time_zone -= 24 * 60;
1029             }
1030           Start = mktime (&tm);
1031         }
1032
1033       if (Start == (time_t) -1)
1034         return Start;
1035     }
1036
1037   if (pc.days_seen && ! pc.dates_seen)
1038     {
1039       tm.tm_mday += ((pc.day_number - tm.tm_wday + 7) % 7
1040                      + 7 * (pc.day_ordinal - (0 < pc.day_ordinal)));
1041       tm.tm_isdst = -1;
1042       Start = mktime (&tm);
1043       if (Start == (time_t) -1)
1044         return Start;
1045     }
1046
1047   if (pc.zones_seen)
1048     {
1049       int delta = pc.time_zone * 60;
1050 #ifdef HAVE_TM_GMTOFF
1051       delta -= tm.tm_gmtoff;
1052 #else
1053       struct tm *gmt = gmtime (&Start);
1054       if (! gmt)
1055         return -1;
1056       delta -= tm_diff (&tm, gmt);
1057 #endif
1058       if ((Start < Start - delta) != (delta < 0))
1059         return -1;      /* time_t overflow */
1060       Start -= delta;
1061     }
1062
1063   /* Add relative hours, minutes, and seconds.  Ignore leap seconds;
1064      i.e. "+ 10 minutes" means 600 seconds, even if one of them is a
1065      leap second.  Typically this is not what the user wants, but it's
1066      too hard to do it the other way, because the time zone indicator
1067      must be applied before relative times, and if mktime is applied
1068      again the time zone will be lost.  */
1069   {
1070     time_t t0 = Start;
1071     long d1 = 60 * 60 * (long) pc.rel_hour;
1072     time_t t1 = t0 + d1;
1073     long d2 = 60 * (long) pc.rel_minutes;
1074     time_t t2 = t1 + d2;
1075     int d3 = pc.rel_seconds;
1076     time_t t3 = t2 + d3;
1077     if ((d1 / (60 * 60) ^ pc.rel_hour)
1078         | (d2 / 60 ^ pc.rel_minutes)
1079         | ((t0 + d1 < t0) ^ (d1 < 0))
1080         | ((t1 + d2 < t1) ^ (d2 < 0))
1081         | ((t2 + d3 < t2) ^ (d3 < 0)))
1082       return -1;
1083     Start = t3;
1084   }
1085
1086   return Start;
1087 }
1088
1089 #if TEST
1090
1091 #include <stdio.h>
1092
1093 int
1094 main (int ac, char **av)
1095 {
1096   char buff[BUFSIZ];
1097   time_t d;
1098
1099   printf ("Enter date, or blank line to exit.\n\t> ");
1100   fflush (stdout);
1101
1102   buff[BUFSIZ - 1] = 0;
1103   while (fgets (buff, BUFSIZ - 1, stdin) && buff[0])
1104     {
1105       d = get_date (buff, 0);
1106       if (d == (time_t) -1)
1107         printf ("Bad format - couldn't convert.\n");
1108       else
1109         printf ("%s", ctime (&d));
1110       printf ("\t> ");
1111       fflush (stdout);
1112     }
1113   return 0;
1114 }
1115 #endif /* defined TEST */