xref: /freebsd-11-stable/usr.bin/find/getdate.y

%{
/*
**  Originally written by Steven M. Bellovin <smb@research.att.com> while
**  at the University of North Carolina at Chapel Hill.  Later tweaked by
**  a couple of people on Usenet.  Completely overhauled by Rich $alz
**  <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990;
**
**  This grammar has 10 shift/reduce conflicts.
**
**  This code is in the public domain and has no copyright.
*/
/* SUPPRESS 287 on yaccpar_sccsid *//* Unused static variable */
/* SUPPRESS 288 on yyerrlab *//* Label unused */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <stdio.h>
#include <ctype.h>

/* The code at the top of get_date which figures out the offset of the
   current time zone checks various CPP symbols to see if special
   tricks are need, but defaults to using the gettimeofday system call.
   Include <sys/time.h> if that will be used.  */

#if	defined(vms)
# include <types.h>
#else /* defined(vms) */
# include <sys/types.h>
# include <sys/time.h>
#endif	/* !defined(vms) */

#if defined (__STDC__) || defined (USG)
#include <string.h>
#endif

/* Some old versions of bison generate parsers that use bcopy.
   That loses on systems that don't provide the function, so we have
   to redefine it here.  */
#if !defined (HAVE_BCOPY) && defined (HAVE_MEMCPY) && !defined (bcopy)
#define bcopy(from, to, len) memcpy ((to), (from), (len))
#endif

#if defined (__STDC__)
#include <stdlib.h>
#endif

/* NOTES on rebuilding getdate.c (particularly for inclusion in CVS
   releases):

   We don't want to mess with all the portability hassles of alloca.
   In particular, most (all?) versions of bison will use alloca in
   their parser.  If bison works on your system (e.g. it should work
   with gcc), then go ahead and use it, but the more general solution
   is to use byacc instead of bison, which should generate a portable
   parser.  I played with adding "#define alloca dont_use_alloca", to
   give an error if the parser generator uses alloca (and thus detect
   unportable getdate.c's), but that seems to cause as many problems
   as it solves.  */

#include <time.h>

#define yylex getdate_yylex
#define yyerror getdate_yyerror

static int yylex(void);
static int yyerror(const char *);

time_t get_date(char *);

#define EPOCH		1970
#define HOUR(x)		((time_t)(x) * 60)
#define SECSPERDAY	(24L * 60L * 60L)


/*
**  An entry in the lexical lookup table.
*/
typedef struct _TABLE {
    const char	*name;
    int		type;
    time_t	value;
} TABLE;


/*
**  Daylight-savings mode:  on, off, or not yet known.
*/
typedef enum _DSTMODE {
    DSTon, DSToff, DSTmaybe
} DSTMODE;

/*
**  Meridian:  am, pm, or 24-hour style.
*/
typedef enum _MERIDIAN {
    MERam, MERpm, MER24
} MERIDIAN;


/*
**  Global variables.  We could get rid of most of these by using a good
**  union as the yacc stack.  (This routine was originally written before
**  yacc had the %union construct.)  Maybe someday; right now we only use
**  the %union very rarely.
*/
static char	*yyInput;
static DSTMODE	yyDSTmode;
static time_t	yyDayOrdinal;
static time_t	yyDayNumber;
static int	yyHaveDate;
static int	yyHaveDay;
static int	yyHaveRel;
static int	yyHaveTime;
static int	yyHaveZone;
static time_t	yyTimezone;
static time_t	yyDay;
static time_t	yyHour;
static time_t	yyMinutes;
static time_t	yyMonth;
static time_t	yySeconds;
static time_t	yyYear;
static MERIDIAN	yyMeridian;
static time_t	yyRelMonth;
static time_t	yyRelSeconds;

%}

%union {
    time_t		Number;
    enum _MERIDIAN	Meridian;
}

%token	tAGO tDAY tDAYZONE tID tMERIDIAN tMINUTE_UNIT tMONTH tMONTH_UNIT
%token	tSEC_UNIT tSNUMBER tUNUMBER tZONE tDST

%type	<Number>	tDAY tDAYZONE tMINUTE_UNIT tMONTH tMONTH_UNIT
%type	<Number>	tSEC_UNIT tSNUMBER tUNUMBER tZONE
%type	<Meridian>	tMERIDIAN o_merid

%%

spec	: /* NULL */
	| spec item
	;

item	: time {
	    yyHaveTime++;
	}
	| zone {
	    yyHaveZone++;
	}
	| date {
	    yyHaveDate++;
	}
	| day {
	    yyHaveDay++;
	}
	| rel {
	    yyHaveRel++;
	}
	| number
	;

time	: tUNUMBER tMERIDIAN {
	    yyHour = $1;
	    yyMinutes = 0;
	    yySeconds = 0;
	    yyMeridian = $2;
	}
	| tUNUMBER ':' tUNUMBER o_merid {
	    yyHour = $1;
	    yyMinutes = $3;
	    yySeconds = 0;
	    yyMeridian = $4;
	}
	| tUNUMBER ':' tUNUMBER tSNUMBER {
	    yyHour = $1;
	    yyMinutes = $3;
	    yyMeridian = MER24;
	    yyDSTmode = DSToff;
	    yyTimezone = - ($4 % 100 + ($4 / 100) * 60);
	}
	| tUNUMBER ':' tUNUMBER ':' tUNUMBER o_merid {
	    yyHour = $1;
	    yyMinutes = $3;
	    yySeconds = $5;
	    yyMeridian = $6;
	}
	| tUNUMBER ':' tUNUMBER ':' tUNUMBER tSNUMBER {
	    yyHour = $1;
	    yyMinutes = $3;
	    yySeconds = $5;
	    yyMeridian = MER24;
	    yyDSTmode = DSToff;
	    yyTimezone = - ($6 % 100 + ($6 / 100) * 60);
	}
	;

zone	: tZONE {
	    yyTimezone = $1;
	    yyDSTmode = DSToff;
	}
	| tDAYZONE {
	    yyTimezone = $1;
	    yyDSTmode = DSTon;
	}
	|
	  tZONE tDST {
	    yyTimezone = $1;
	    yyDSTmode = DSTon;
	}
	;

day	: tDAY {
	    yyDayOrdinal = 1;
	    yyDayNumber = $1;
	}
	| tDAY ',' {
	    yyDayOrdinal = 1;
	    yyDayNumber = $1;
	}
	| tUNUMBER tDAY {
	    yyDayOrdinal = $1;
	    yyDayNumber = $2;
	}
	;

date	: tUNUMBER '/' tUNUMBER {
	    yyMonth = $1;
	    yyDay = $3;
	}
	| tUNUMBER '/' tUNUMBER '/' tUNUMBER {
	    if ($1 >= 100) {
		yyYear = $1;
		yyMonth = $3;
		yyDay = $5;
	    } else {
		yyMonth = $1;
		yyDay = $3;
		yyYear = $5;
	    }
	}
	| tUNUMBER tSNUMBER tSNUMBER {
	    /* ISO 8601 format.  yyyy-mm-dd.  */
	    yyYear = $1;
	    yyMonth = -$2;
	    yyDay = -$3;
	}
	| tUNUMBER tMONTH tSNUMBER {
	    /* e.g. 17-JUN-1992.  */
	    yyDay = $1;
	    yyMonth = $2;
	    yyYear = -$3;
	}
	| tMONTH tUNUMBER {
	    yyMonth = $1;
	    yyDay = $2;
	}
	| tMONTH tUNUMBER ',' tUNUMBER {
	    yyMonth = $1;
	    yyDay = $2;
	    yyYear = $4;
	}
	| tUNUMBER tMONTH {
	    yyMonth = $2;
	    yyDay = $1;
	}
	| tUNUMBER tMONTH tUNUMBER {
	    yyMonth = $2;
	    yyDay = $1;
	    yyYear = $3;
	}
	;

rel	: relunit tAGO {
	    yyRelSeconds = -yyRelSeconds;
	    yyRelMonth = -yyRelMonth;
	}
	| relunit
	;

relunit	: tUNUMBER tMINUTE_UNIT {
	    yyRelSeconds += $1 * $2 * 60L;
	}
	| tSNUMBER tMINUTE_UNIT {
	    yyRelSeconds += $1 * $2 * 60L;
	}
	| tMINUTE_UNIT {
	    yyRelSeconds += $1 * 60L;
	}
	| tSNUMBER tSEC_UNIT {
	    yyRelSeconds += $1;
	}
	| tUNUMBER tSEC_UNIT {
	    yyRelSeconds += $1;
	}
	| tSEC_UNIT {
	    yyRelSeconds++;
	}
	| tSNUMBER tMONTH_UNIT {
	    yyRelMonth += $1 * $2;
	}
	| tUNUMBER tMONTH_UNIT {
	    yyRelMonth += $1 * $2;
	}
	| tMONTH_UNIT {
	    yyRelMonth += $1;
	}
	;

number	: tUNUMBER {
	    if (yyHaveTime && yyHaveDate && !yyHaveRel)
		yyYear = $1;
	    else {
		if($1>10000) {
		    yyHaveDate++;
		    yyDay= ($1)%100;
		    yyMonth= ($1/100)%100;
		    yyYear = $1/10000;
		}
		else {
		    yyHaveTime++;
		    if ($1 < 100) {
			yyHour = $1;
			yyMinutes = 0;
		    }
		    else {
		    	yyHour = $1 / 100;
		    	yyMinutes = $1 % 100;
		    }
		    yySeconds = 0;
		    yyMeridian = MER24;
	        }
	    }
	}
	;

o_merid	: /* NULL */ {
	    $$ = MER24;
	}
	| tMERIDIAN {
	    $$ = $1;
	}
	;

%%

/* Month and day table. */
static TABLE const MonthDayTable[] = {
    { "january",	tMONTH,  1 },
    { "february",	tMONTH,  2 },
    { "march",		tMONTH,  3 },
    { "april",		tMONTH,  4 },
    { "may",		tMONTH,  5 },
    { "june",		tMONTH,  6 },
    { "july",		tMONTH,  7 },
    { "august",		tMONTH,  8 },
    { "september",	tMONTH,  9 },
    { "sept",		tMONTH,  9 },
    { "october",	tMONTH, 10 },
    { "november",	tMONTH, 11 },
    { "december",	tMONTH, 12 },
    { "sunday",		tDAY, 0 },
    { "monday",		tDAY, 1 },
    { "tuesday",	tDAY, 2 },
    { "tues",		tDAY, 2 },
    { "wednesday",	tDAY, 3 },
    { "wednes",		tDAY, 3 },
    { "thursday",	tDAY, 4 },
    { "thur",		tDAY, 4 },
    { "thurs",		tDAY, 4 },
    { "friday",		tDAY, 5 },
    { "saturday",	tDAY, 6 },
    { NULL,		0, 0 }
};

/* Time units table. */
static TABLE const UnitsTable[] = {
    { "year",		tMONTH_UNIT,	12 },
    { "month",		tMONTH_UNIT,	1 },
    { "fortnight",	tMINUTE_UNIT,	14 * 24 * 60 },
    { "week",		tMINUTE_UNIT,	7 * 24 * 60 },
    { "day",		tMINUTE_UNIT,	1 * 24 * 60 },
    { "hour",		tMINUTE_UNIT,	60 },
    { "minute",		tMINUTE_UNIT,	1 },
    { "min",		tMINUTE_UNIT,	1 },
    { "second",		tSEC_UNIT,	1 },
    { "sec",		tSEC_UNIT,	1 },
    { NULL,		0,		0 }
};

/* Assorted relative-time words. */
static TABLE const OtherTable[] = {
    { "tomorrow",	tMINUTE_UNIT,	1 * 24 * 60 },
    { "yesterday",	tMINUTE_UNIT,	-1 * 24 * 60 },
    { "today",		tMINUTE_UNIT,	0 },
    { "now",		tMINUTE_UNIT,	0 },
    { "last",		tUNUMBER,	-1 },
    { "this",		tMINUTE_UNIT,	0 },
    { "next",		tUNUMBER,	2 },
    { "first",		tUNUMBER,	1 },
/*  { "second",		tUNUMBER,	2 }, */
    { "third",		tUNUMBER,	3 },
    { "fourth",		tUNUMBER,	4 },
    { "fifth",		tUNUMBER,	5 },
    { "sixth",		tUNUMBER,	6 },
    { "seventh",	tUNUMBER,	7 },
    { "eighth",		tUNUMBER,	8 },
    { "ninth",		tUNUMBER,	9 },
    { "tenth",		tUNUMBER,	10 },
    { "eleventh",	tUNUMBER,	11 },
    { "twelfth",	tUNUMBER,	12 },
    { "ago",		tAGO,		1 },
    { NULL,		0,		0 }
};

/* The timezone table. */
/* Some of these are commented out because a time_t can't store a float. */
static TABLE const TimezoneTable[] = {
    { "gmt",	tZONE,     HOUR( 0) },	/* Greenwich Mean */
    { "ut",	tZONE,     HOUR( 0) },	/* Universal (Coordinated) */
    { "utc",	tZONE,     HOUR( 0) },
    { "wet",	tZONE,     HOUR( 0) },	/* Western European */
    { "bst",	tDAYZONE,  HOUR( 0) },	/* British Summer */
    { "wat",	tZONE,     HOUR( 1) },	/* West Africa */
    { "at",	tZONE,     HOUR( 2) },	/* Azores */
#if	0
    /* For completeness.  BST is also British Summer, and GST is
     * also Guam Standard. */
    { "bst",	tZONE,     HOUR( 3) },	/* Brazil Standard */
    { "gst",	tZONE,     HOUR( 3) },	/* Greenland Standard */
#endif
#if 0
    { "nft",	tZONE,     HOUR(3.5) },	/* Newfoundland */
    { "nst",	tZONE,     HOUR(3.5) },	/* Newfoundland Standard */
    { "ndt",	tDAYZONE,  HOUR(3.5) },	/* Newfoundland Daylight */
#endif
    { "ast",	tZONE,     HOUR( 4) },	/* Atlantic Standard */
    { "adt",	tDAYZONE,  HOUR( 4) },	/* Atlantic Daylight */
    { "est",	tZONE,     HOUR( 5) },	/* Eastern Standard */
    { "edt",	tDAYZONE,  HOUR( 5) },	/* Eastern Daylight */
    { "cst",	tZONE,     HOUR( 6) },	/* Central Standard */
    { "cdt",	tDAYZONE,  HOUR( 6) },	/* Central Daylight */
    { "mst",	tZONE,     HOUR( 7) },	/* Mountain Standard */
    { "mdt",	tDAYZONE,  HOUR( 7) },	/* Mountain Daylight */
    { "pst",	tZONE,     HOUR( 8) },	/* Pacific Standard */
    { "pdt",	tDAYZONE,  HOUR( 8) },	/* Pacific Daylight */
    { "yst",	tZONE,     HOUR( 9) },	/* Yukon Standard */
    { "ydt",	tDAYZONE,  HOUR( 9) },	/* Yukon Daylight */
    { "hst",	tZONE,     HOUR(10) },	/* Hawaii Standard */
    { "hdt",	tDAYZONE,  HOUR(10) },	/* Hawaii Daylight */
    { "cat",	tZONE,     HOUR(10) },	/* Central Alaska */
    { "ahst",	tZONE,     HOUR(10) },	/* Alaska-Hawaii Standard */
    { "nt",	tZONE,     HOUR(11) },	/* Nome */
    { "idlw",	tZONE,     HOUR(12) },	/* International Date Line West */
    { "cet",	tZONE,     -HOUR(1) },	/* Central European */
    { "met",	tZONE,     -HOUR(1) },	/* Middle European */
    { "mewt",	tZONE,     -HOUR(1) },	/* Middle European Winter */
    { "mest",	tDAYZONE,  -HOUR(1) },	/* Middle European Summer */
    { "swt",	tZONE,     -HOUR(1) },	/* Swedish Winter */
    { "sst",	tDAYZONE,  -HOUR(1) },	/* Swedish Summer */
    { "fwt",	tZONE,     -HOUR(1) },	/* French Winter */
    { "fst",	tDAYZONE,  -HOUR(1) },	/* French Summer */
    { "eet",	tZONE,     -HOUR(2) },	/* Eastern Europe, USSR Zone 1 */
    { "bt",	tZONE,     -HOUR(3) },	/* Baghdad, USSR Zone 2 */
#if 0
    { "it",	tZONE,     -HOUR(3.5) },/* Iran */
#endif
    { "zp4",	tZONE,     -HOUR(4) },	/* USSR Zone 3 */
    { "zp5",	tZONE,     -HOUR(5) },	/* USSR Zone 4 */
#if 0
    { "ist",	tZONE,     -HOUR(5.5) },/* Indian Standard */
#endif
    { "zp6",	tZONE,     -HOUR(6) },	/* USSR Zone 5 */
#if	0
    /* For completeness.  NST is also Newfoundland Stanard, and SST is
     * also Swedish Summer. */
    { "nst",	tZONE,     -HOUR(6.5) },/* North Sumatra */
    { "sst",	tZONE,     -HOUR(7) },	/* South Sumatra, USSR Zone 6 */
#endif	/* 0 */
    { "wast",	tZONE,     -HOUR(7) },	/* West Australian Standard */
    { "wadt",	tDAYZONE,  -HOUR(7) },	/* West Australian Daylight */
#if 0
    { "jt",	tZONE,     -HOUR(7.5) },/* Java (3pm in Cronusland!) */
#endif
    { "cct",	tZONE,     -HOUR(8) },	/* China Coast, USSR Zone 7 */
    { "jst",	tZONE,     -HOUR(9) },	/* Japan Standard, USSR Zone 8 */
#if 0
    { "cast",	tZONE,     -HOUR(9.5) },/* Central Australian Standard */
    { "cadt",	tDAYZONE,  -HOUR(9.5) },/* Central Australian Daylight */
#endif
    { "east",	tZONE,     -HOUR(10) },	/* Eastern Australian Standard */
    { "eadt",	tDAYZONE,  -HOUR(10) },	/* Eastern Australian Daylight */
    { "gst",	tZONE,     -HOUR(10) },	/* Guam Standard, USSR Zone 9 */
    { "nzt",	tZONE,     -HOUR(12) },	/* New Zealand */
    { "nzst",	tZONE,     -HOUR(12) },	/* New Zealand Standard */
    { "nzdt",	tDAYZONE,  -HOUR(12) },	/* New Zealand Daylight */
    { "idle",	tZONE,     -HOUR(12) },	/* International Date Line East */
    {  NULL,	0,	   0 }
};

/* Military timezone table. */
static TABLE const MilitaryTable[] = {
    { "a",	tZONE,	HOUR(  1) },
    { "b",	tZONE,	HOUR(  2) },
    { "c",	tZONE,	HOUR(  3) },
    { "d",	tZONE,	HOUR(  4) },
    { "e",	tZONE,	HOUR(  5) },
    { "f",	tZONE,	HOUR(  6) },
    { "g",	tZONE,	HOUR(  7) },
    { "h",	tZONE,	HOUR(  8) },
    { "i",	tZONE,	HOUR(  9) },
    { "k",	tZONE,	HOUR( 10) },
    { "l",	tZONE,	HOUR( 11) },
    { "m",	tZONE,	HOUR( 12) },
    { "n",	tZONE,	HOUR(- 1) },
    { "o",	tZONE,	HOUR(- 2) },
    { "p",	tZONE,	HOUR(- 3) },
    { "q",	tZONE,	HOUR(- 4) },
    { "r",	tZONE,	HOUR(- 5) },
    { "s",	tZONE,	HOUR(- 6) },
    { "t",	tZONE,	HOUR(- 7) },
    { "u",	tZONE,	HOUR(- 8) },
    { "v",	tZONE,	HOUR(- 9) },
    { "w",	tZONE,	HOUR(-10) },
    { "x",	tZONE,	HOUR(-11) },
    { "y",	tZONE,	HOUR(-12) },
    { "z",	tZONE,	HOUR(  0) },
    { NULL,	0,	0 }
};




/* ARGSUSED */
static int
yyerror(const char *s __unused)
{
  return 0;
}


static time_t
ToSeconds(time_t Hours, time_t Minutes, time_t Seconds, MERIDIAN Meridian)
{
    if (Minutes < 0 || Minutes > 59 || Seconds < 0 || Seconds > 59)
	return -1;
    switch (Meridian) {
    case MER24:
	if (Hours < 0 || Hours > 23)
	    return -1;
	return (Hours * 60L + Minutes) * 60L + Seconds;
    case MERam:
	if (Hours < 1 || Hours > 12)
	    return -1;
	if (Hours == 12)
	    Hours = 0;
	return (Hours * 60L + Minutes) * 60L + Seconds;
    case MERpm:
	if (Hours < 1 || Hours > 12)
	    return -1;
	if (Hours == 12)
	    Hours = 0;
	return ((Hours + 12) * 60L + Minutes) * 60L + Seconds;
    default:
	abort ();
    }
    /* NOTREACHED */
}


/* Year is either
   * A negative number, which means to use its absolute value (why?)
   * A number from 0 to 99, which means a year from 1900 to 1999, or
   * The actual year (>=100).  */
static time_t
Convert(time_t Month, time_t Day, time_t Year,
	time_t Hours, time_t Minutes, time_t Seconds,
	MERIDIAN Meridian, DSTMODE DSTmode)
{
    static int DaysInMonth[12] = {
	31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
    };
    time_t	tod;
    time_t	Julian;
    int		i;

    if (Year < 0)
	Year = -Year;
    if (Year < 69)
	Year += 2000;
    else if (Year < 100)
	Year += 1900;
    DaysInMonth[1] = Year % 4 == 0 && (Year % 100 != 0 || Year % 400 == 0)
		    ? 29 : 28;
    /* Checking for 2038 bogusly assumes that time_t is 32 bits.  But
       I'm too lazy to try to check for time_t overflow in another way.  */
    if (Year < EPOCH || Year > 2038
     || Month < 1 || Month > 12
     /* Lint fluff:  "conversion from long may lose accuracy" */
     || Day < 1 || Day > DaysInMonth[(int)--Month])
	return -1;

    for (Julian = Day - 1, i = 0; i < Month; i++)
	Julian += DaysInMonth[i];
    for (i = EPOCH; i < Year; i++)
	Julian += 365 + (i % 4 == 0);
    Julian *= SECSPERDAY;
    Julian += yyTimezone * 60L;
    if ((tod = ToSeconds(Hours, Minutes, Seconds, Meridian)) < 0)
	return -1;
    Julian += tod;
    if (DSTmode == DSTon
     || (DSTmode == DSTmaybe && localtime(&Julian)->tm_isdst))
	Julian -= 60 * 60;
    return Julian;
}


static time_t
DSTcorrect(time_t Start, time_t Future)
{
    time_t	StartDay;
    time_t	FutureDay;

    StartDay = (localtime(&Start)->tm_hour + 1) % 24;
    FutureDay = (localtime(&Future)->tm_hour + 1) % 24;
    return (Future - Start) + (StartDay - FutureDay) * 60L * 60L;
}


static time_t
RelativeDate(time_t Start, time_t DayOrdinal, time_t DayNumber)
{
    struct tm	*tm;
    time_t	now;

    now = Start;
    tm = localtime(&now);
    now += SECSPERDAY * ((DayNumber - tm->tm_wday + 7) % 7);
    now += 7 * SECSPERDAY * (DayOrdinal <= 0 ? DayOrdinal : DayOrdinal - 1);
    return DSTcorrect(Start, now);
}


static time_t
RelativeMonth(time_t Start, time_t RelMonth)
{
    struct tm	*tm;
    time_t	Month;
    time_t	Year;

    if (RelMonth == 0)
	return 0;
    tm = localtime(&Start);
    Month = 12 * (tm->tm_year + 1900) + tm->tm_mon + RelMonth;
    Year = Month / 12;
    Month = Month % 12 + 1;
    return DSTcorrect(Start,
	    Convert(Month, (time_t)tm->tm_mday, Year,
		(time_t)tm->tm_hour, (time_t)tm->tm_min, (time_t)tm->tm_sec,
		MER24, DSTmaybe));
}


static int
LookupWord(char *buff)
{
    char	*p;
    char	*q;
    const TABLE	*tp;
    int		i;
    int		abbrev;

    /* Make it lowercase. */
    for (p = buff; *p; p++)
	if (isupper(*p))
	    *p = tolower(*p);

    if (strcmp(buff, "am") == 0 || strcmp(buff, "a.m.") == 0) {
	yylval.Meridian = MERam;
	return tMERIDIAN;
    }
    if (strcmp(buff, "pm") == 0 || strcmp(buff, "p.m.") == 0) {
	yylval.Meridian = MERpm;
	return tMERIDIAN;
    }

    /* See if we have an abbreviation for a month. */
    if (strlen(buff) == 3)
	abbrev = 1;
    else if (strlen(buff) == 4 && buff[3] == '.') {
	abbrev = 1;
	buff[3] = '\0';
    }
    else
	abbrev = 0;

    for (tp = MonthDayTable; tp->name; tp++) {
	if (abbrev) {
	    if (strncmp(buff, tp->name, 3) == 0) {
		yylval.Number = tp->value;
		return tp->type;
	    }
	}
	else if (strcmp(buff, tp->name) == 0) {
	    yylval.Number = tp->value;
	    return tp->type;
	}
    }

    for (tp = TimezoneTable; tp->name; tp++)
	if (strcmp(buff, tp->name) == 0) {
	    yylval.Number = tp->value;
	    return tp->type;
	}

    if (strcmp(buff, "dst") == 0)
	return tDST;

    for (tp = UnitsTable; tp->name; tp++)
	if (strcmp(buff, tp->name) == 0) {
	    yylval.Number = tp->value;
	    return tp->type;
	}

    /* Strip off any plural and try the units table again. */
    i = strlen(buff) - 1;
    if (buff[i] == 's') {
	buff[i] = '\0';
	for (tp = UnitsTable; tp->name; tp++)
	    if (strcmp(buff, tp->name) == 0) {
		yylval.Number = tp->value;
		return tp->type;
	    }
	buff[i] = 's';		/* Put back for "this" in OtherTable. */
    }

    for (tp = OtherTable; tp->name; tp++)
	if (strcmp(buff, tp->name) == 0) {
	    yylval.Number = tp->value;
	    return tp->type;
	}

    /* Military timezones. */
    if (buff[1] == '\0' && isalpha(*buff)) {
	for (tp = MilitaryTable; tp->name; tp++)
	    if (strcmp(buff, tp->name) == 0) {
		yylval.Number = tp->value;
		return tp->type;
	    }
    }

    /* Drop out any periods and try the timezone table again. */
    for (i = 0, p = q = buff; *q; q++)
	if (*q != '.')
	    *p++ = *q;
	else
	    i++;
    *p = '\0';
    if (i)
	for (tp = TimezoneTable; tp->name; tp++)
	    if (strcmp(buff, tp->name) == 0) {
		yylval.Number = tp->value;
		return tp->type;
	    }

    return tID;
}


static int
yylex(void)
{
    char	c;
    char	*p;
    char	buff[20];
    int		Count;
    int		sign;

    for ( ; ; ) {
	while (isspace(*yyInput))
	    yyInput++;

	if (isdigit(c = *yyInput) || c == '-' || c == '+') {
	    if (c == '-' || c == '+') {
		sign = c == '-' ? -1 : 1;
		if (!isdigit(*++yyInput))
		    /* skip the '-' sign */
		    continue;
	    }
	    else
		sign = 0;
	    for (yylval.Number = 0; isdigit(c = *yyInput++); )
		yylval.Number = 10 * yylval.Number + c - '0';
	    yyInput--;
	    if (sign < 0)
		yylval.Number = -yylval.Number;
	    return sign ? tSNUMBER : tUNUMBER;
	}
	if (isalpha(c)) {
	    for (p = buff; isalpha(c = *yyInput++) || c == '.'; )
		if (p < &buff[sizeof buff - 1])
		    *p++ = c;
	    *p = '\0';
	    yyInput--;
	    return LookupWord(buff);
	}
	if (c != '(')
	    return *yyInput++;
	Count = 0;
	do {
	    c = *yyInput++;
	    if (c == '\0')
		return c;
	    if (c == '(')
		Count++;
	    else if (c == ')')
		Count--;
	} while (Count > 0);
    }
}

#define TM_YEAR_ORIGIN 1900

/* Yield A - B, measured in seconds.  */
static long
difftm (struct tm *a, struct tm *b)
{
  int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
  int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
  int days = (
	      /* difference in day of year */
	      a->tm_yday - b->tm_yday
	      /* + intervening leap days */
	      +  ((ay >> 2) - (by >> 2))
	      -  (ay/100 - by/100)
	      +  ((ay/100 >> 2) - (by/100 >> 2))
	      /* + difference in years * 365 */
	      +  (long)(ay-by) * 365
	      );
  return (60*(60*(24*days + (a->tm_hour - b->tm_hour))
	      + (a->tm_min - b->tm_min))
	  + (a->tm_sec - b->tm_sec));
}

time_t
get_date(char *p)
{
    struct tm		*tm, *gmt_ptr, gmt;
    int			tzoff;
    time_t		Start;
    time_t		tod;
    time_t nowtime;

    bzero (&gmt, sizeof(struct tm));
    yyInput = p;

    (void)time (&nowtime);

    gmt_ptr = gmtime (&nowtime);
    if (gmt_ptr != NULL)
    {
	/* Make a copy, in case localtime modifies *tm (I think
	   that comment now applies to *gmt_ptr, but I am too
	   lazy to dig into how gmtime and locatime allocate the
	   structures they return pointers to).  */
	gmt = *gmt_ptr;
    }

    if (! (tm = localtime (&nowtime)))
	return -1;

    if (gmt_ptr != NULL)
	tzoff = difftm (&gmt, tm) / 60;
    else
	/* We are on a system like VMS, where the system clock is
	   in local time and the system has no concept of timezones.
	   Hopefully we can fake this out (for the case in which the
	   user specifies no timezone) by just saying the timezone
	   is zero.  */
	tzoff = 0;

    if(tm->tm_isdst)
	tzoff += 60;

    tm = localtime(&nowtime);
    yyYear = tm->tm_year + 1900;
    yyMonth = tm->tm_mon + 1;
    yyDay = tm->tm_mday;
    yyTimezone = tzoff;
    yyDSTmode = DSTmaybe;
    yyHour = 0;
    yyMinutes = 0;
    yySeconds = 0;
    yyMeridian = MER24;
    yyRelSeconds = 0;
    yyRelMonth = 0;
    yyHaveDate = 0;
    yyHaveDay = 0;
    yyHaveRel = 0;
    yyHaveTime = 0;
    yyHaveZone = 0;

    if (yyparse()
     || yyHaveTime > 1 || yyHaveZone > 1 || yyHaveDate > 1 || yyHaveDay > 1)
	return -1;

    if (yyHaveDate || yyHaveTime || yyHaveDay) {
	Start = Convert(yyMonth, yyDay, yyYear, yyHour, yyMinutes, yySeconds,
		    yyMeridian, yyDSTmode);
	if (Start < 0)
	    return -1;
    }
    else {
	Start = nowtime;
	if (!yyHaveRel)
	    Start -= ((tm->tm_hour * 60L + tm->tm_min) * 60L) + tm->tm_sec;
    }

    Start += yyRelSeconds;
    Start += RelativeMonth(Start, yyRelMonth);

    if (yyHaveDay && !yyHaveDate) {
	tod = RelativeDate(Start, yyDayOrdinal, yyDayNumber);
	Start += tod;
    }

    /* Have to do *something* with a legitimate -1 so it's distinguishable
     * from the error return value.  (Alternately could set errno on error.) */
    return Start == -1 ? 0 : Start;
}


#if	defined(TEST)

/* ARGSUSED */
int
main(int ac, char *av[])
{
    char	buff[128];
    time_t	d;

    (void)printf("Enter date, or blank line to exit.\n\t> ");
    (void)fflush(stdout);
    while (gets(buff) && buff[0]) {
	d = get_date(buff);
	if (d == -1)
	    (void)printf("Bad format - couldn't convert.\n");
	else
	    (void)printf("%s", ctime(&d));
	(void)printf("\t> ");
	(void)fflush(stdout);
    }
    exit(0);
    /* NOTREACHED */
}
#endif	/* defined(TEST) */