parsedate.y

%{
/* $Revision: 1.16 $
**
**  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@osf.org> and Jim Berets <jberets@bbn.com> in August, 1990.
**  Further revised (removed obsolete constructs and cleaned up timezone
**  names) in August, 1991, by Rich.  Paul Eggert <eggert@twinsun.com>
**  helped in September, 1992.
**
**  This grammar has six shift/reduce conflicts.
**
**  This code is in the public domain and has no copyright.
*/
/* SUPPRESS 530 *//* Empty body for statement */
/* SUPPRESS 593 on yyerrlab *//* Label was not used */
/* SUPPRESS 593 on yynewstate *//* Label was not used */
/* SUPPRESS 595 on yypvt *//* Automatic variable may be used before set */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <ctype.h>
#include <time.h>
#include <string.h>

int date_lex();

#define yyparse		date_parse
#define yylex		date_lex
#define yyerror		date_error


    /* See the LeapYears table in Convert. */
#define EPOCH		1970
#define END_OF_TIME	2038
    /* Constants for general time calculations. */
#define DST_OFFSET	1
#define SECSPERDAY	(24L * 60L * 60L)
    /* Readability for TABLE stuff. */
#define HOUR(x)		(x * 60)

#define LPAREN		'('
#define RPAREN		')'
#define IS7BIT(x)	((unsigned int)(x) < 0200)

#define SIZEOF(array)	((int)(sizeof array / sizeof array[0]))
#define ENDOF(array)	(&array[SIZEOF(array)])


/*
**  An entry in the lexical lookup table.
*/
typedef struct _TABLE {
    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 them by using a yacc
**  union, but this is more efficient.  (This routine predates the
**  yacc %union construct.)
*/
static char	*yyInput;
static DSTMODE	yyDSTmode;
static int	yyHaveDate;
static int	yyHaveRel;
static int	yyHaveTime;
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;


extern struct tm	*localtime();
static void		date_error();
%}

%union {
    time_t		Number;
    enum _MERIDIAN	Meridian;
}

%token	tDAY tDAYZONE tMERIDIAN tMONTH tMONTH_UNIT tSEC_UNIT tSNUMBER
%token	tUNUMBER tZONE

%type	<Number>	tDAYZONE tMONTH tMONTH_UNIT tSEC_UNIT
%type	<Number>	tSNUMBER tUNUMBER tZONE numzone zone
%type	<Meridian>	tMERIDIAN o_merid

%%

spec	: /* NULL */
	| spec item
	;

item	: time {
	    yyHaveTime++;
#ifdef lint
	    /* I am compulsive about lint natterings... */
	    if (yyHaveTime == -1) {
		YYERROR;
	    }
#endif /* lint */
	}
	| time zone {
	    yyHaveTime++;
	    yyTimezone = $2;
	}
	| date {
	    yyHaveDate++;
	}
	| rel {
	    yyHaveRel = 1;
	}
	;

time	: tUNUMBER o_merid {
	    if ($1 < 100) {
		yyHour = $1;
		yyMinutes = 0;
	    }
	    else {
		yyHour = $1 / 100;
		yyMinutes = $1 % 100;
	    }
	    yySeconds = 0;
	    yyMeridian = $2;
	}
	| tUNUMBER ':' tUNUMBER o_merid {
	    yyHour = $1;
	    yyMinutes = $3;
	    yySeconds = 0;
	    yyMeridian = $4;
	}
	| tUNUMBER ':' tUNUMBER numzone {
	    yyHour = $1;
	    yyMinutes = $3;
	    yyTimezone = $4;
	    yyMeridian = MER24;
	    yyDSTmode = DSToff;
	}
	| tUNUMBER ':' tUNUMBER ':' tUNUMBER o_merid {
	    yyHour = $1;
	    yyMinutes = $3;
	    yySeconds = $5;
	    yyMeridian = $6;
	}
	| tUNUMBER ':' tUNUMBER ':' tUNUMBER numzone {
	    yyHour = $1;
	    yyMinutes = $3;
	    yySeconds = $5;
	    yyTimezone = $6;
	    yyMeridian = MER24;
	    yyDSTmode = DSToff;
	}
	;

zone	: tZONE {
	    $$ = $1;
	    yyDSTmode = DSToff;
	}
	| tDAYZONE {
	    $$ = $1;
	    yyDSTmode = DSTon;
	}
	| tZONE numzone {
	    /* Only allow "GMT+300" and "GMT-0800" */
	    if ($1 != 0) {
		YYABORT;
	    }
	    $$ = $2;
	    yyDSTmode = DSToff;
	}
	| numzone {
	    $$ = $1;
	    yyDSTmode = DSToff;
	}
	;

numzone	: tSNUMBER {
	    int		i;

	    /* Unix and GMT and numeric timezones -- a little confusing. */
	    if ($1 < 0) {
		/* Don't work with negative modulus. */
		$1 = -$1;
		if ($1 > 9999 || (i = $1 % 100) >= 60) {
		    YYABORT;
		}
		$$ = ($1 / 100) * 60 + i;
	    }
	    else {
		if ($1 > 9999 || (i = $1 % 100) >= 60) {
		    YYABORT;
		}
		$$ = -(($1 / 100) * 60 + i);
	    }
	}
	;

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;
	    }
	}
	| tMONTH tUNUMBER {
	    yyMonth = $1;
	    yyDay = $2;
	}
	| tMONTH tUNUMBER ',' tUNUMBER {
	    yyMonth = $1;
	    yyDay = $2;
	    yyYear = $4;
	}
	| tUNUMBER tMONTH {
	    yyDay = $1;
	    yyMonth = $2;
	}
	| tUNUMBER tMONTH tUNUMBER {
	    yyDay = $1;
	    yyMonth = $2;
	    yyYear = $3;
	}
	| tDAY ',' tUNUMBER tMONTH tUNUMBER {
	    yyDay = $3;
	    yyMonth = $4;
	    yyYear = $5;
	}
	;

rel	: tSNUMBER tSEC_UNIT {
	    yyRelSeconds += $1 * $2;
	}
	| tUNUMBER tSEC_UNIT {
	    yyRelSeconds += $1 * $2;
	}
	| tSNUMBER tMONTH_UNIT {
	    yyRelMonth += $1 * $2;
	}
	| tUNUMBER tMONTH_UNIT {
	    yyRelMonth += $1 * $2;
	}
	;

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

%%

/* Month and day table. */
static TABLE	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 },
    { "october",	tMONTH, 10 },
    { "november",	tMONTH, 11 },
    { "december",	tMONTH, 12 },
	/* The value of the day isn't used... */
    { "sunday",		tDAY, 0 },
    { "monday",		tDAY, 0 },
    { "tuesday",	tDAY, 0 },
    { "wednesday",	tDAY, 0 },
    { "thursday",	tDAY, 0 },
    { "friday",		tDAY, 0 },
    { "saturday",	tDAY, 0 },
};

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

/* Timezone table. */
static TABLE	TimezoneTable[] = {
    { "gmt",	tZONE,     HOUR( 0) },	/* Greenwich Mean */
    { "ut",	tZONE,     HOUR( 0) },	/* Universal */
    { "utc",	tZONE,     HOUR( 0) },	/* Universal Coordinated */
    { "cut",	tZONE,     HOUR( 0) },	/* Coordinated Universal */
    { "z",	tZONE,     HOUR( 0) },	/* Greenwich Mean */
    { "wet",	tZONE,     HOUR( 0) },	/* Western European */
    { "bst",	tDAYZONE,  HOUR( 0) },	/* British Summer */
    { "nst",	tZONE,     HOUR(3)+30 }, /* Newfoundland Standard */
    { "ndt",	tDAYZONE,  HOUR(3)+30 }, /* Newfoundland Daylight */
    { "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 */
    { "akst",	tZONE,     HOUR( 9) },	/* Alaska Standard */
    { "akdt",	tDAYZONE,  HOUR( 9) },	/* Alaska Daylight */
    { "hst",	tZONE,     HOUR(10) },	/* Hawaii Standard */
    { "hast",	tZONE,     HOUR(10) },	/* Hawaii-Aleutian Standard */
    { "hadt",	tDAYZONE,  HOUR(10) },	/* Hawaii-Aleutian Daylight */
    { "ces",	tDAYZONE,  -HOUR(1) },	/* Central European Summer */
    { "cest",	tDAYZONE,  -HOUR(1) },	/* Central European Summer */
    { "mez",	tZONE,     -HOUR(1) },	/* Middle European */
    { "mezt",	tDAYZONE,  -HOUR(1) },	/* Middle European Summer */
    { "cet",	tZONE,     -HOUR(1) },	/* Central European */
    { "met",	tZONE,     -HOUR(1) },	/* Middle European */
    { "eet",	tZONE,     -HOUR(2) },	/* Eastern Europe */
    { "msk",	tZONE,     -HOUR(3) },	/* Moscow Winter */
    { "msd",	tDAYZONE,  -HOUR(3) },	/* Moscow Summer */
    { "wast",	tZONE,     -HOUR(8) },	/* West Australian Standard */
    { "wadt",	tDAYZONE,  -HOUR(8) },	/* West Australian Daylight */
    { "hkt",	tZONE,     -HOUR(8) },	/* Hong Kong */
    { "cct",	tZONE,     -HOUR(8) },	/* China Coast */
    { "jst",	tZONE,     -HOUR(9) },	/* Japan Standard */
    { "kst",	tZONE,     -HOUR(9) },	/* Korean Standard */
    { "kdt",	tZONE,     -HOUR(9) },	/* Korean Daylight */
    { "cast",	tZONE,     -(HOUR(9)+30) }, /* Central Australian Standard */
    { "cadt",	tDAYZONE,  -(HOUR(9)+30) }, /* Central Australian Daylight */
    { "east",	tZONE,     -HOUR(10) },	/* Eastern Australian Standard */
    { "eadt",	tDAYZONE,  -HOUR(10) },	/* Eastern Australian Daylight */
    { "nzst",	tZONE,     -HOUR(12) },	/* New Zealand Standard */
    { "nzdt",	tDAYZONE,  -HOUR(12) },	/* New Zealand Daylight */

    /* For completeness we include the following entries. */
#if 0

    /* Duplicate names.  Either they conflict with a zone listed above
     * (which is either more likely to be seen or just been in circulation
     * longer), or they conflict with another zone in this section and
     * we could not reasonably choose one over the other. */
    { "fst",	tZONE,     HOUR( 2) },	/* Fernando De Noronha Standard */
    { "fdt",	tDAYZONE,  HOUR( 2) },	/* Fernando De Noronha Daylight */
    { "bst",	tZONE,     HOUR( 3) },	/* Brazil Standard */
    { "est",	tZONE,     HOUR( 3) },	/* Eastern Standard (Brazil) */
    { "edt",	tDAYZONE,  HOUR( 3) },	/* Eastern Daylight (Brazil) */
    { "wst",	tZONE,     HOUR( 4) },	/* Western Standard (Brazil) */
    { "wdt",	tDAYZONE,  HOUR( 4) },	/* Western Daylight (Brazil) */
    { "cst",	tZONE,     HOUR( 5) },	/* Chile Standard */
    { "cdt",	tDAYZONE,  HOUR( 5) },	/* Chile Daylight */
    { "ast",	tZONE,     HOUR( 5) },	/* Acre Standard */
    { "adt",	tDAYZONE,  HOUR( 5) },	/* Acre Daylight */
    { "cst",	tZONE,     HOUR( 5) },	/* Cuba Standard */
    { "cdt",	tDAYZONE,  HOUR( 5) },	/* Cuba Daylight */
    { "est",	tZONE,     HOUR( 6) },	/* Easter Island Standard */
    { "edt",	tDAYZONE,  HOUR( 6) },	/* Easter Island Daylight */
    { "sst",	tZONE,     HOUR(11) },	/* Samoa Standard */
    { "ist",	tZONE,     -HOUR(2) },	/* Israel Standard */
    { "idt",	tDAYZONE,  -HOUR(2) },	/* Israel Daylight */
    { "idt",	tDAYZONE,  -(HOUR(3)+30) }, /* Iran Daylight */
    { "ist",	tZONE,     -(HOUR(3)+30) }, /* Iran Standard */
    { "cst",	 tZONE,     -HOUR(8) },	/* China Standard */
    { "cdt",	 tDAYZONE,  -HOUR(8) },	/* China Daylight */
    { "sst",	 tZONE,     -HOUR(8) },	/* Singapore Standard */

    /* Dubious (e.g., not in Olson's TIMEZONE package) or obsolete. */
    { "gst",	tZONE,     HOUR( 3) },	/* Greenland Standard */
    { "wat",	tZONE,     -HOUR(1) },	/* West Africa */
    { "at",	tZONE,     HOUR( 2) },	/* Azores */
    { "gst",	tZONE,     -HOUR(10) },	/* Guam Standard */
    { "nft",	tZONE,     HOUR(3)+30 }, /* Newfoundland */
    { "idlw",	tZONE,     HOUR(12) },	/* International Date Line West */
    { "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 */
    { "bt",	tZONE,     -HOUR(3) },	/* Baghdad */
    { "it",	tZONE,     -(HOUR(3)+30) }, /* Iran */
    { "zp4",	tZONE,     -HOUR(4) },	/* USSR Zone 3 */
    { "zp5",	tZONE,     -HOUR(5) },	/* USSR Zone 4 */
    { "ist",	tZONE,     -(HOUR(5)+30) }, /* Indian Standard */
    { "zp6",	tZONE,     -HOUR(6) },	/* USSR Zone 5 */
    { "nst",	tZONE,     -HOUR(7) },	/* North Sumatra */
    { "sst",	tZONE,     -HOUR(7) },	/* South Sumatra */
    { "jt",	tZONE,     -(HOUR(7)+30) }, /* Java (3pm in Cronusland!) */
    { "nzt",	tZONE,     -HOUR(12) },	/* New Zealand */
    { "idle",	tZONE,     -HOUR(12) },	/* International Date Line East */
    { "cat",	tZONE,     HOUR(10) },	/* -- expired 1967 */
    { "nt",	tZONE,     HOUR(11) },	/* -- expired 1967 */
    { "ahst",	tZONE,     HOUR(10) },	/* -- expired 1983 */
    { "hdt",	tDAYZONE,  HOUR(10) },	/* -- expired 1986 */
#endif /* 0 */
};


/* ARGSUSED */
static void
date_error(s)
    char	*s;
{
    /* NOTREACHED */
}


static time_t
ToSeconds(Hours, Minutes, Seconds, Meridian)
    time_t	Hours;
    time_t	Minutes;
    time_t	Seconds;
    MERIDIAN	Meridian;
{
    if (Minutes < 0 || Minutes > 59 || Seconds < 0 || Seconds > 61)
	return -1;
    if (Meridian == MER24) {
	if (Hours < 0 || Hours > 23)
	    return -1;
    }
    else {
	if (Hours < 1 || Hours > 12)
	    return -1;
	if (Hours == 12)
	    Hours = 0;
	if (Meridian == MERpm)
	    Hours += 12;
    }
    return (Hours * 60L + Minutes) * 60L + Seconds;
}


static time_t
Convert(Month, Day, Year, Hours, Minutes, Seconds, Meridian, dst)
    time_t	Month;
    time_t	Day;
    time_t	Year;
    time_t	Hours;
    time_t	Minutes;
    time_t	Seconds;
    MERIDIAN	Meridian;
    DSTMODE	dst;
{
    static int	DaysNormal[13] = {
	0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
    };
    static int	DaysLeap[13] = {
	0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
    };
    static int	LeapYears[] = {
	1972, 1976, 1980, 1984, 1988, 1992, 1996,
	2000, 2004, 2008, 2012, 2016, 2020, 2024, 2028, 2032, 2036
    };
    register int	*yp;
    register int	*mp;
    register time_t	Julian;
    register int	i;
    time_t		tod;

    if (Year < 0)
	Year = -Year;
    if (Year < 100)
	Year += 1900;
    if (Year < EPOCH)
	Year += 100;
    for (mp = DaysNormal, yp = LeapYears; yp < ENDOF(LeapYears); yp++)
	if (Year == *yp) {
	    mp = DaysLeap;
	    break;
	}
    if (Year < EPOCH || Year > END_OF_TIME
     || Month < 1 || Month > 12
     /* NOSTRICT *//* conversion from long may lose accuracy */
     || Day < 1 || Day > mp[(int)Month])
	return -1;

    Julian = Day - 1 + (Year - EPOCH) * 365;
    for (yp = LeapYears; yp < ENDOF(LeapYears); yp++, Julian++)
	if (Year <= *yp)
	    break;
    for (i = 1; i < Month; i++)
	Julian += *++mp;
    Julian *= SECSPERDAY;
    Julian += yyTimezone * 60L;
    if ((tod = ToSeconds(Hours, Minutes, Seconds, Meridian)) < 0)
	return -1;
    Julian += tod;
    tod = Julian;
    if (dst == DSTon || (dst == DSTmaybe && localtime(&tod)->tm_isdst))
	Julian -= DST_OFFSET * 60L * 60L;
    return Julian;
}


static time_t
DSTcorrect(Start, Future)
    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) * DST_OFFSET * 60L * 60L;
}


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

    tm = localtime(&Start);
    Month = 12 * tm->tm_year + 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(buff, length)
    char		*buff;
    register int	length;
{
    register char	*p;
    register char	*q;
    register TABLE	*tp;
    register int	c;

    p = buff;
    c = p[0];

    /* See if we have an abbreviation for a month. */
    if (length == 3 || (length == 4 && p[3] == '.'))
	for (tp = MonthDayTable; tp < ENDOF(MonthDayTable); tp++) {
	    q = tp->name;
	    if (c == q[0] && p[1] == q[1] && p[2] == q[2]) {
		yylval.Number = tp->value;
		return tp->type;
	    }
	}
    else
	for (tp = MonthDayTable; tp < ENDOF(MonthDayTable); tp++)
	    if (c == tp->name[0] && strcmp(p, tp->name) == 0) {
		yylval.Number = tp->value;
		return tp->type;
	    }

    /* Try for a timezone. */
    for (tp = TimezoneTable; tp < ENDOF(TimezoneTable); tp++)
	if (c == tp->name[0] && p[1] == tp->name[1]
	 && strcmp(p, tp->name) == 0) {
	    yylval.Number = tp->value;
	    return tp->type;
	}

    /* Try the units table. */
    for (tp = UnitsTable; tp < ENDOF(UnitsTable); tp++)
	if (c == tp->name[0] && strcmp(p, tp->name) == 0) {
	    yylval.Number = tp->value;
	    return tp->type;
	}

    /* Strip off any plural and try the units table again. */
    if (--length > 0 && p[length] == 's') {
	p[length] = '\0';
	for (tp = UnitsTable; tp < ENDOF(UnitsTable); tp++)
	    if (c == tp->name[0] && strcmp(p, tp->name) == 0) {
		p[length] = 's';
		yylval.Number = tp->value;
		return tp->type;
	    }
	p[length] = 's';
    }
    length++;

    /* Drop out any periods. */
    for (p = buff, q = (char*)buff; *q; q++)
	if (*q != '.')
	    *p++ = *q;
    *p = '\0';

    /* Try the meridians. */
    if (buff[1] == 'm' && buff[2] == '\0') {
	if (buff[0] == 'a') {
	    yylval.Meridian = MERam;
	    return tMERIDIAN;
	}
	if (buff[0] == 'p') {
	    yylval.Meridian = MERpm;
	    return tMERIDIAN;
	}
    }

    /* If we saw any periods, try the timezones again. */
    if (p - buff != length) {
	c = buff[0];
	for (p = buff, tp = TimezoneTable; tp < ENDOF(TimezoneTable); tp++)
	    if (c == tp->name[0] && p[1] == tp->name[1]
	    && strcmp(p, tp->name) == 0) {
		yylval.Number = tp->value;
		return tp->type;
	    }
    }

    /* Unknown word -- assume GMT timezone. */
    yylval.Number = 0;
    return tZONE;
}


int
date_lex()
{
    register char	c;
    register char	*p;
    char		buff[20];
    register int	sign;
    register int	i;
    register int	nesting;

    for ( ; ; ) {
	/* Get first character after the whitespace. */
	for ( ; ; ) {
	    while (isspace(*yyInput))
		yyInput++;
	    c = *yyInput;

	    /* Ignore RFC 822 comments, typically time zone names. */
	    if (c != LPAREN)
		break;
	    for (nesting = 1; (c = *++yyInput) != RPAREN || --nesting; )
		if (c == LPAREN)
		    nesting++;
		else if (!IS7BIT(c) || c == '\0' || c == '\r'
		     || (c == '\\' && ((c = *++yyInput) == '\0' || !IS7BIT(c))))
		    /* Lexical error: bad comment. */
		    return '?';
	    yyInput++;
	}

	/* A number? */
	if (isdigit(c) || c == '-' || c == '+') {
	    if (c == '-' || c == '+') {
		sign = c == '-' ? -1 : 1;
		yyInput++;
		if (!isdigit(*yyInput))
		    /* Skip the plus or minus sign. */
		    continue;
	    }
	    else
		sign = 0;
	    for (i = 0; (c = *yyInput++) != '\0' && isdigit(c); )
		i = 10 * i + c - '0';
	    yyInput--;
	    yylval.Number = sign < 0 ? -i : i;
	    return sign ? tSNUMBER : tUNUMBER;
	}

	/* A word? */
	if (isalpha(c)) {
	    for (p = buff; (c = *yyInput++) == '.' || isalpha(c); )
		if (p < &buff[sizeof buff - 1])
		    *p++ = isupper(c) ? tolower(c) : c;
	    *p = '\0';
	    yyInput--;
	    return LookupWord(buff, p - buff);
	}

	return *yyInput++;
    }
}


time_t
parsedate(p)
    char		*p;
{
    extern int		date_parse();
    time_t		Start;

    yyInput = p;

    yyYear = 0;
    yyMonth = 0;
    yyDay = 0;
    yyTimezone = 0;
    yyDSTmode = DSTmaybe;
    yyHour = 0;
    yyMinutes = 0;
    yySeconds = 0;
    yyMeridian = MER24;
    yyRelSeconds = 0;
    yyRelMonth = 0;
    yyHaveDate = 0;
    yyHaveRel = 0;
    yyHaveTime = 0;

    if (date_parse() || yyHaveTime > 1 || yyHaveDate > 1)
	return -1;

    if (yyHaveDate || yyHaveTime) {
	Start = Convert(yyMonth, yyDay, yyYear, yyHour, yyMinutes, yySeconds,
		    yyMeridian, yyDSTmode);
	if (Start < 0)
	    return -1;
    }
    else
	return -1;

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

    /* 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;
}


#ifdef TEST

#if YYDEBUG
extern int	yydebug;
#endif /* YYDEBUG */

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

#if YYDEBUG
    yydebug = 1;
#endif /* YYDEBUG */

    (void)printf("Enter date, or blank line to exit.\n\t> ");
    for ( ; ; ) {
	(void)printf("\t> ");
	(void)fflush(stdout);
	if (gets(buff) == NULL || buff[0] == '\n')
	    break;
#if YYDEBUG
	if (strcmp(buff, "yydebug") == 0) {
	    yydebug = !yydebug;
	    printf("yydebug = %s\n", yydebug ? "on" : "off");
	    continue;
	}
#endif /* YYDEBUG */
	d = parsedate(buff, (TIMEINFO *)NULL);
	if (d == -1)
	    (void)printf("Bad format - couldn't convert.\n");
	else
	    (void)printf("%s", ctime(&d));
    }

    exit(0);
    /* NOTREACHED */
}
#endif /* TEST */