nabstime.c

/*-------------------------------------------------------------------------
 *
 * nabstime.c--
 *    parse almost any absolute date getdate(3) can (& some it can't)
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/utils/adt/nabstime.c,v 1.13 1997/01/27 01:51:21 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <sys/types.h>

#include "postgres.h"
#ifndef USE_POSIX_TIME
#include <sys/timeb.h>
#endif
#include "access/xact.h"

#define MAXDATEFIELDS 25

#define ISSPACE(c) ((c) == ' ' || (c) == '\n' || (c) == '\t')

/* this is fast but dirty.  note the return's in the middle. */
#define GOBBLE_NUM(cp, c, x, ip) \
	(c) = *(cp)++; \
	if ((c) < '0' || (c) > '9') \
		return -1;		/* missing digit */ \
	(x) = (c) - '0'; \
	(c) = *(cp)++; \
	if ((c) >= '0' && (c) <= '9') { \
		(x) = 10*(x) + (c) - '0'; \
		(c) = *(cp)++; \
	} \
	if ((c) != ':' && (c) != '\0' && !ISSPACE(c)) \
		return -1;		/* missing colon */ \
	*(ip) = (x)			/* N.B.: no semi-colon here */

#define EPOCH 1970
#define DAYS_PER_400YRS	(time_t)146097
#define DAYS_PER_4YRS	(time_t)1461
#define SECS_PER_DAY	86400
#define SECS_PER_HOUR	3600
#define DIVBY4(n) ((n) >> 2)
#define YRNUM(c, y) (DIVBY4(DAYS_PER_400YRS*(c)) + DIVBY4(DAYS_PER_4YRS*(y)))
#define DAYNUM(c,y,mon,d)	(YRNUM((c), (y)) + mdays[mon] + (d))
#define EPOCH_DAYNUM	DAYNUM(19, 69, 10, 1)	/* really January 1, 1970 */
#define MIN_DAYNUM -24856			/* December 13, 1901 */
#define MAX_DAYNUM 24854			/* January 18, 2038 */

/* definitions for squeezing values into "value" */
#define ABS_SIGNBIT 0200
#define VALMASK 0177
#define NEG(n)		((n)|ABS_SIGNBIT)
#define SIGNEDCHAR(c)	((c)&ABS_SIGNBIT? -((c)&VALMASK): (c))
#define FROMVAL(tp)	(-SIGNEDCHAR((tp)->value) * 10)	/* uncompress */
#define TOVAL(tp, v)	((tp)->value = ((v) < 0? NEG((-(v))/10): (v)/10))
#define IsLeapYear(yr) ((yr%4) == 0)

char nmdays[] = {
	0, 31, 28, 31,  30, 31, 30,  31, 31, 30,  31, 30, 31
};
/* days since start of year. mdays[0] is March, mdays[11] is February */
static short mdays[] = {
	0, 31, 61, 92, 122, 153, 184, 214, 245, 275, 306, 337
};

/* exports */
static int dtok_numparsed;

/*
 * to keep this table reasonably small, we divide the lexval for TZ and DTZ
 * entries by 10 and truncate the text field at MAXTOKLEN characters.
 * the text field is not guaranteed to be NUL-terminated.
 */
static datetkn datetktbl[] = {
/*	text		token	lexval */
{	"acsst",	DTZ,	63},		/* Cent. Australia */
{	"acst",		TZ,	57},		/* Cent. Australia */
{	"adt",		DTZ,	NEG(18)},	/* Atlantic Daylight Time */
{	"aesst",	DTZ,	66},		/* E. Australia */
{	"aest",		TZ,	60},		/* Australia Eastern Std Time */
{	"ahst",		TZ,	60},		/* Alaska-Hawaii Std Time */
{	"am",		AMPM,	AM},
{	"apr",		MONTH,	4},
{	"april",	MONTH,	4},
{	"ast",		TZ,	NEG(24)},	/* Atlantic Std Time (Canada) */
{	"at",		PG_IGNORE,	0},		/* "at" (throwaway) */
{	"aug",		MONTH,	8},
{	"august",	MONTH,	8},
{	"awsst",	DTZ,	54},		/* W. Australia */
{	"awst",		TZ,	48},		/* W. Australia */
{	"bst",		TZ,	6},		/* British Summer Time */
{	"bt",		TZ,	18},		/* Baghdad Time */
{	"cadt",		DTZ,	63},		/* Central Australian DST */
{	"cast",		TZ,	57},		/* Central Australian ST */
{	"cat",		TZ,	NEG(60)},	/* Central Alaska Time */
{	"cct",		TZ,	48},		/* China Coast */
{	"cdt",		DTZ,	NEG(30)},	/* Central Daylight Time */
{	"cet",		TZ,	6},		/* Central European Time */
{	"cetdst",	DTZ,	12},		/* Central European Dayl.Time */
{	"cst",		TZ,	NEG(36)},	/* Central Standard Time */
{	"dec",		MONTH,	12},
{	"decemb",	MONTH,	12},
{	"dnt",		TZ,	6},		/* Dansk Normal Tid */
{	"dst",		PG_IGNORE,	0},
{	"east",		TZ,	NEG(60)},	/* East Australian Std Time */
{	"edt",		DTZ,	NEG(24)},	/* Eastern Daylight Time */
{	"eet",		TZ,	12},		/* East. Europe, USSR Zone 1 */
{	"eetdst",	DTZ,	18},		/* Eastern Europe */
{	"est",		TZ,	NEG(30)},	/* Eastern Standard Time */
{	"feb",		MONTH,	2},
{	"februa",	MONTH,	2},
{	"fri",		PG_IGNORE,	5},
{	"friday",	PG_IGNORE,	5},
{	"fst",		TZ,	6},		/* French Summer Time */
{	"fwt",		DTZ,	12},		/* French Winter Time  */
{	"gmt",		TZ,	0},		/* Greenwish Mean Time */
{	"gst",		TZ,	60},		/* Guam Std Time, USSR Zone 9 */
{	"hdt",		DTZ,	NEG(54)},	/* Hawaii/Alaska */
{	"hmt",		DTZ,	18},		/* Hellas ? ? */
{	"hst",		TZ,	NEG(60)},	/* Hawaii Std Time */
{	"idle",		TZ,	72},		/* Intl. Date Line, East */
{	"idlw",		TZ,	NEG(72)},	/* Intl. Date Line, West */
{	"ist",		TZ,	12},		/* Israel */
{	"it",		TZ,	22},		/* Iran Time */
{	"jan",		MONTH,	1},
{	"januar",	MONTH,	1},
{	"jst",		TZ,	54},		/* Japan Std Time,USSR Zone 8 */
{	"jt",		TZ,	45},		/* Java Time */
{	"jul",		MONTH,	7},
{	"july",		MONTH,	7},
{	"jun",		MONTH,	6},
{	"june",		MONTH,	6},
{	"kst",		TZ,	54},		/* Korea Standard Time */
{	"ligt",		TZ,	60},		/* From Melbourne, Australia */
{	"mar",		MONTH,	3},
{	"march",	MONTH,	3},
{	"may",		MONTH,	5},
{	"mdt",		DTZ,	NEG(36)},	/* Mountain Daylight Time */
{	"mest",		DTZ,	12},		/* Middle Europe Summer Time */
{	"met",		TZ,	6},		/* Middle Europe Time */
{	"metdst",	DTZ,	12},		/* Middle Europe Daylight Time*/
{	"mewt",		TZ,	6},		/* Middle Europe Winter Time */
{	"mez",		TZ,	6},		/* Middle Europe Zone */
{	"mon",		PG_IGNORE,	1},
{	"monday",	PG_IGNORE,	1},
{	"mst",		TZ,	NEG(42)},	/* Mountain Standard Time */
{	"mt",		TZ,	51},		/* Moluccas Time */
{	"ndt",		DTZ,	NEG(15)},	/* Nfld. Daylight Time */
{	"nft",		TZ,	NEG(21)},	/* Newfoundland Standard Time */
{	"nor",		TZ,	6},		/* Norway Standard Time */
{	"nov",		MONTH,	11},
{	"novemb",	MONTH,	11},
{	"nst",		TZ,	NEG(21)},	/* Nfld. Standard Time */
{	"nt",		TZ,	NEG(66)},	/* Nome Time */
{	"nzdt",		DTZ,	78},		/* New Zealand Daylight Time */
{	"nzst",		TZ,	72},		/* New Zealand Standard Time */
{	"nzt",		TZ,	72},		/* New Zealand Time */
{	"oct",		MONTH,	10},
{	"octobe",	MONTH,	10},
{	"on",		PG_IGNORE,	0},		/* "on" (throwaway) */
{	"pdt",		DTZ,	NEG(42)},	/* Pacific Daylight Time */
{	"pm",		AMPM,	PM},
{	"pst",		TZ,	NEG(48)},	/* Pacific Standard Time */
{	"sadt",		DTZ,	63},		/* S. Australian Dayl. Time */
{	"sast",		TZ,	57},		/* South Australian Std Time */
{	"sat",		PG_IGNORE,	6},
{	"saturd",	PG_IGNORE,	6},
{	"sep",		MONTH,	9},
{	"sept",		MONTH,	9},
{	"septem",	MONTH,	9},
{	"set",		TZ,	NEG(6)},	/* Seychelles Time ?? */
{	"sst",		DTZ,	12},		/* Swedish Summer Time */
{	"sun",		PG_IGNORE,	0},
{	"sunday",	PG_IGNORE,	0},
{	"swt",		TZ,	6},		/* Swedish Winter Time  */
{	"thu",		PG_IGNORE,	4},
{	"thur",		PG_IGNORE,	4},
{	"thurs",	PG_IGNORE,	4},
{	"thursd",	PG_IGNORE,	4},
{	"tue",		PG_IGNORE,	2},
{	"tues",		PG_IGNORE,	2},
{	"tuesda",	PG_IGNORE,	2},
{	"ut",		TZ,	0},
{	"utc",		TZ,	0},
{	"wadt",		DTZ,	48},		/* West Australian DST */
{	"wast",		TZ,	42},		/* West Australian Std Time */
{	"wat",		TZ,	NEG(6)},	/* West Africa Time */
{	"wdt",		DTZ,	54},		/* West Australian DST */
{	"wed",		PG_IGNORE,	3},
{	"wednes",	PG_IGNORE,	3},
{	"weds",		PG_IGNORE,	3},
{	"wet",		TZ,	0},		/* Western Europe */
{	"wetdst",	DTZ,	6},		/* Western Europe */
{	"wst",		TZ,	48},		/* West Australian Std Time */
{	"ydt",		DTZ,	NEG(48)},	/* Yukon Daylight Time */
{	"yst",		TZ,	NEG(54)},	/* Yukon Standard Time */
{	"zp4",		TZ,	NEG(24)},	/* GMT +4  hours. */
{	"zp5",		TZ,	NEG(30)},	/* GMT +5  hours. */
{	"zp6",		TZ,	NEG(36)},	/* GMT +6  hours. */
};

static unsigned int szdatetktbl = sizeof datetktbl / sizeof datetktbl[0];

/*
 * parse and convert absolute date in timestr (the normal interface)
 *
 * Returns the number of seconds since epoch (January 1 1970 GMT)
 */
AbsoluteTime
nabstimein(char* timestr)
{
    int tz = 0;
    struct tm date;
    
    if (!timestr)
	return INVALID_ABSTIME;
    while (ISSPACE(*timestr))
	++timestr;
    
    if (!strcasecmp(timestr, "epoch"))
	return EPOCH_ABSTIME;
    if (!strcasecmp(timestr, "now"))
	return GetCurrentTransactionStartTime();
    if (!strcasecmp(timestr, "current"))
	return CURRENT_ABSTIME;
    if (!strcasecmp(timestr, "infinity"))
	return NOEND_ABSTIME;
    if (!strcasecmp(timestr, "-infinity"))
	return NOSTART_ABSTIME;
    if (prsabsdate(timestr, &date, &tz) < 0)
	return INVALID_ABSTIME;
    return dateconv(&date, tz);
}

/*
 * just parse the absolute date in timestr and get back a broken-out date.
 */
int
prsabsdate(char *timestr,
	   struct tm *tm,
	   int *tzp)		/* - minutes west */
{
    register int nf;
    char *fields[MAXDATEFIELDS];
    static char delims[] = "- \t\n/,";
    
    nf = split(timestr, fields, MAXDATEFIELDS, delims+1);
    if (nf > MAXDATEFIELDS)
	return -1;
    if (tryabsdate(fields, nf, tm, tzp) < 0) {
	register char *p = timestr;
	
	/*
	 * could be a DEC-date; glue it all back together, split it
	 * with dash as a delimiter and try again.  Yes, this is a
	 * hack, but so are DEC-dates.
	 */
	while (--nf > 0) {
	    while (*p++ != '\0')
		;
	    p[-1] = ' ';
	}
	nf = split(timestr, fields, MAXDATEFIELDS, delims);
	if (nf > MAXDATEFIELDS)
	    return -1;
	if (tryabsdate(fields, nf, tm, tzp) < 0)
	    return -1;
    }
    return 0;
}

/*
 * try to parse pre-split timestr as an absolute date
 */
int
tryabsdate(char *fields[], int nf, struct tm *tm, int *tzp)
{
    register int i;
    register datetkn *tp;
    register long flg = 0, ty;
    int mer = HR24, bigval = -1;
#ifndef USE_POSIX_TIME
    struct timeb now;		/* the old V7-ism */
    
    (void) ftime(&now);
    *tzp = now.timezone;
#else /* USE_POSIX_TIME */
#if defined(HAVE_TZSET) && defined(HAVE_INT_TIMEZONE)
	    tzset();
#ifndef win32
    *tzp = timezone / 60;		/* this is an X/Open-ism */
#else
    *tzp = _timezone / 60;            /* this is an X/Open-ism */
#endif /* win32 */
#else /* !HAVE_TZSET */
    time_t now = time((time_t *) NULL);
    struct tm *tmnow = localtime(&now);
    
    *tzp = - tmnow->tm_gmtoff / 60;	/* tm_gmtoff is Sun/DEC-ism */
#endif
#endif 
    
    tm->tm_mday = tm->tm_mon = tm->tm_year = -1;	/* mandatory */
    tm->tm_hour = tm->tm_min = tm->tm_sec = 0;
    tm->tm_isdst = -1;             /* assume we don't know. */
    dtok_numparsed = 0;
    
    for (i = 0; i < nf; i++) {
	if (fields[i][0] == '\0')
	    continue;
	tp = datetoktype(fields[i], &bigval);
	ty = (1L << tp->type) & ~(1L << PG_IGNORE);
	if (flg&ty)
	    return -1;		/* repeated type */
	flg |= ty;
	switch (tp->type) {
	case YEAR:
	    tm->tm_year = bigval;
	    break;
	case DAY:
	    tm->tm_mday = bigval;
	    break;
	case MONTH:
	    tm->tm_mon = tp->value;
	    break;
	case TIME:
	    if (parsetime(fields[i], tm) < 0)
		return -1;
	    break;
	case DTZ:
	    tm->tm_isdst++;
	    /* FALLTHROUGH */
	case TZ:
	    *tzp = FROMVAL(tp);
	    break;
	case PG_IGNORE:
	    break;
	case AMPM:
	    mer = tp->value;
	    break;
	default:
	    return -1;	/* bad token type: CANTHAPPEN */
	}
    }
    if (tm->tm_year == -1 || tm->tm_mon == -1 || tm->tm_mday == -1)
	return -1;		/* missing component */
    if (mer == PM)
	tm->tm_hour += 12;
    return 0;
}


/* return -1 on failure */
int
parsetime(char *time, struct tm *tm)
{
    register char c;
    register int x;
    
    tm->tm_sec = 0;
    GOBBLE_NUM(time, c, x, &tm->tm_hour);
    if (c != ':')
	return -1;		/* only hour; too short */
    GOBBLE_NUM(time, c, x, &tm->tm_min);
    if (c != ':')
	return 0;		/* no seconds; okay */
    GOBBLE_NUM(time, c, x, &tm->tm_sec);
    /* this may be considered too strict.  garbage at end of time? */
    return (c == '\0' || ISSPACE(c)? 0: -1);
}


/*
 * split - divide a string into fields, like awk split()
 */
int			/* number of fields, including overflow */
split(char *string,
      char *fields[],	/* list is not NULL-terminated */
      int nfields,	/* number of entries available in fields[] */
      char *sep)	/* "" white, "c" single char, "ab" [ab]+ */
{
    register char *p = string;
    register char c;			/* latest character */
    register char sepc = sep[0];
    register char sepc2;
    register int fn;
    register char **fp = fields;
    register char *sepp;
    register int trimtrail;
    
    /* white space */
    if (sepc == '\0') {
	while ((c = *p++) == ' ' || c == '\t')
	    continue;
	p--;
	trimtrail = 1;
	sep = " \t";	/* note, code below knows this is 2 long */
	sepc = ' ';
    } else
	trimtrail = 0;
    sepc2 = sep[1];		/* now we can safely pick this up */
    
    /* catch empties */
    if (*p == '\0')
	return(0);
    
    /* single separator */
    if (sepc2 == '\0') {
	fn = nfields;
	for (;;) {
	    *fp++ = p;
	    fn--;
	    if (fn == 0)
		break;
	    while ((c = *p++) != sepc)
		if (c == '\0')
		    return(nfields - fn);
	    *(p-1) = '\0';
	}
	/* we have overflowed the fields vector -- just count them */
	fn = nfields;
	for (;;) {
	    while ((c = *p++) != sepc)
		if (c == '\0')
		    return(fn);
	    fn++;
	}
	/* not reached */
    }
    
    /* two separators */
    if (sep[2] == '\0') {
	fn = nfields;
	for (;;) {
	    *fp++ = p;
	    fn--;
	    while ((c = *p++) != sepc && c != sepc2)
		if (c == '\0') {
		    if (trimtrail && **(fp-1) == '\0')
			fn++;
		    return(nfields - fn);
		}
	    if (fn == 0)
		break;
	    *(p-1) = '\0';
	    while ((c = *p++) == sepc || c == sepc2)
		continue;
	    p--;
	}
	/* we have overflowed the fields vector -- just count them */
	fn = nfields;
	while (c != '\0') {
	    while ((c = *p++) == sepc || c == sepc2)
		continue;
	    p--;
	    fn++;
	    while ((c = *p++) != '\0' && c != sepc && c != sepc2)
		continue;
	}
	/* might have to trim trailing white space */
	if (trimtrail) {
	    p--;
	    while ((c = *--p) == sepc || c == sepc2)
		continue;
	    p++;
	    if (*p != '\0') {
		if (fn == nfields+1)
		    *p = '\0';
		fn--;
	    }
	}
	return(fn);
    }
    
    /* n separators */
    fn = 0;
    for (;;) {
	if (fn < nfields)
	    *fp++ = p;
	fn++;
	for (;;) {
	    c = *p++;
	    if (c == '\0')
		return(fn);
	    sepp = sep;
	    while ((sepc = *sepp++) != '\0' && sepc != c)
		continue;
	    if (sepc != '\0')	/* it was a separator */
		break;
	}
	if (fn < nfields)
	    *(p-1) = '\0';
	for (;;) {
	    c = *p++;
	    sepp = sep;
	    while ((sepc = *sepp++) != '\0' && sepc != c)
		continue;
	    if (sepc == '\0')	/* it wasn't a separator */
		break;
	}
	p--;
    }
    
    /* not reached */
}

/*
 * Given an AbsoluteTime return the English text version of the date
 */
char *
nabstimeout(AbsoluteTime time)
{
    /*
     * Fri Jan 28 23:05:29 1994 PST
     * 0        1         2
     * 12345678901234567890123456789
     *
     * we allocate some extra -- timezones are usually 3 characters but
     * this is not in the POSIX standard...
     */
    char buf[40];
    char* result;

    switch (time) {
    case EPOCH_ABSTIME:	  (void) strcpy(buf, "epoch");			break;
    case INVALID_ABSTIME: (void) strcpy(buf, "Invalid Abstime");	break;
    case CURRENT_ABSTIME: (void) strcpy(buf, "current");		break;
    case NOEND_ABSTIME:   (void) strcpy(buf, "infinity");		break;
    case NOSTART_ABSTIME: (void) strcpy(buf, "-infinity");		break;
    default:
	/* hack -- localtime happens to work for negative times */
	(void) strftime(buf, sizeof(buf), "%a %b %d %H:%M:%S %Y %Z",
			localtime((time_t *) &time));
	break;
    }
    result = (char*)palloc(strlen(buf) + 1);
    strcpy(result, buf);
    return result;
}

/* turn a (struct tm) and a few variables into a time_t, with range checking */
AbsoluteTime
dateconv(register struct tm *tm, int zone)
{
    tm->tm_wday = tm->tm_yday = 0;
    
    /* validate, before going out of range on some members */
    if (tm->tm_year < 0 || tm->tm_mon < 1 || tm->tm_mon > 12 ||
	tm->tm_mday < 1 || tm->tm_hour < 0 || tm->tm_hour >= 24 ||
	tm->tm_min < 0 || tm->tm_min > 59 ||
	tm->tm_sec < 0 || tm->tm_sec > 59)
	return -1;
    
    /*
     * zone should really be -zone, and tz should be set to tp->value, not
     * -tp->value.  Or the table could be fixed.
     */
    tm->tm_min += zone;		/* mktime lets it be out of range */
    
    /* convert to seconds */
    return qmktime(tm);
}


/*
 * near-ANSI qmktime suitable for use by dateconv; not necessarily as paranoid
 * as ANSI requires, and it may not canonicalise the struct tm.  Ignores tm_wday
 * and tm_yday.
 */
time_t
qmktime(struct tm *tp)
{
    register int mon = tp->tm_mon;
    register int day = tp->tm_mday, year = tp->tm_year;
    register time_t daynum;
    time_t secondnum;
    register int century;
    
    /* If it was a 2 digit year */
    if (year < 100)
	year += 1900;
    
    /*
     * validate day against days-per-month table, with leap-year
     * correction
     */
    if (day > nmdays[mon])
	if (mon != 2 ||
	    (year % 4 == 0 &&
	    ((year % 100 != 0 || year % 400 == 0)) && day > 29))
	    return -1;	/* day too large for month */
    
    /* split year into century and year-of-century */
    century = year / 100;
    year %= 100;
    /*
     * We calculate the day number exactly, assuming the calendar has
     * always had the current leap year rules.  (The leap year rules are
     * to compensate for the fact that the Earth's revolution around the
     * Sun takes 365.2425 days).  We first need to rotate months so March
     * is 0, since we want the last month to have the reduced number of
     * days.
     */
    if (mon > 2)
	mon -= 3;
    else {
	mon += 9;
	if (year == 0) {
	    century--;
	    year = 99;
	} else
	    --year;
    }
    daynum = -EPOCH_DAYNUM + DAYNUM(century, year, mon, day);
    
    /* check for time out of range */
    if (daynum < MIN_DAYNUM || daynum > MAX_DAYNUM)
	return INVALID_ABSTIME;
    
    /* convert to seconds */
    secondnum =
	tp->tm_sec + (tp->tm_min +(daynum*24 + tp->tm_hour)*60)*60;
    
    /* check for overflow */
    if ((daynum == MAX_DAYNUM && secondnum < 0) ||
	(daynum == MIN_DAYNUM && secondnum > 0))
	return INVALID_ABSTIME;
    
    /* check for "current", "infinity", "-infinity" */
    if (!AbsoluteTimeIsReal(secondnum))
	return INVALID_ABSTIME;
    
    /* daylight correction */
    if (tp->tm_isdst < 0)		/* unknown; find out */
     {
       struct tm *result;
 
       /* NT returns NULL for any time before 1/1/70 */
       result = localtime(&secondnum);
       if (result == NULL)
           return INVALID_ABSTIME;
       else
           tp->tm_isdst = result->tm_isdst;
     }
    if (tp->tm_isdst > 0)
	secondnum -= 60*60;
    
    return secondnum;
}

datetkn *
datetoktype(char *s, int *bigvalp)
{
    register char *cp = s;
    register char c = *cp;
    static datetkn t;
    register datetkn *tp = &t;
    
    if (isascii(c) && isdigit(c)) {
	register int len = strlen(cp);
	
	if (len > 3 && (cp[1] == ':' || cp[2] == ':'))
	    tp->type = TIME;
	else {
	    if (bigvalp != NULL)
		/* won't fit in tp->value */
		*bigvalp = atoi(cp);
	    if (len == 4)
		tp->type = YEAR;
	    else if (++dtok_numparsed == 1)
		tp->type = DAY;
	    else
		tp->type = YEAR;
	}
    } else if (c == '-' || c == '+') {
	register int val = atoi(cp + 1);
	register int hr =  val / 100;
	register int min = val % 100;
	
	val = hr*60 + min;
	if (c == '-')
	    val = -val;
	tp->type = TZ;
	TOVAL(tp, val);
    } else {
	char lowtoken[TOKMAXLEN+1];
	register char *ltp = lowtoken, *endltp = lowtoken+TOKMAXLEN;
	
	/* copy to lowtoken to avoid modifying s */
	while ((c = *cp++) != '\0' && ltp < endltp)
	    *ltp++ = (isascii(c) && isupper(c)? tolower(c): c);
	*ltp = '\0';
	tp = datebsearch(lowtoken, datetktbl, szdatetktbl);
	if (tp == NULL) {
	    tp = &t;
	    tp->type = PG_IGNORE;
	}
    }
    return tp;
}

/*
 * Binary search -- from Knuth (6.2.1) Algorithm B.  Special case like this
 * is WAY faster than the generic bsearch().
 */
datetkn *
datebsearch(char *key, datetkn *base, unsigned int nel)
{
    register datetkn *last = base + nel - 1, *position;
    register int result;
    
    while (last >= base) {
	position = base + ((last - base) >> 1);
	result = key[0] - position->token[0];
	if (result == 0) {
	    result = strncmp(key, position->token, TOKMAXLEN);
	    if (result == 0)
		return position;
	}
	if (result < 0)
	    last = position - 1;
	else
	    base = position + 1;
    }
    return 0;
}


/*
 *  AbsoluteTimeIsBefore -- true iff time1 is before time2.
 */

bool
AbsoluteTimeIsBefore(AbsoluteTime time1, AbsoluteTime time2)
{
    AbsoluteTime tm = GetCurrentTransactionStartTime();
    
    Assert(AbsoluteTimeIsValid(time1));
    Assert(AbsoluteTimeIsValid(time2));
    
    if ((time1 == CURRENT_ABSTIME) || (time2 == CURRENT_ABSTIME))
	return false;
    if (time1 == CURRENT_ABSTIME)
	return (tm < time2);
    if (time2 == CURRENT_ABSTIME)
	return (time1 < tm);
    
    return (time1 < time2);
}

bool
AbsoluteTimeIsAfter(AbsoluteTime time1, AbsoluteTime time2)
{
    AbsoluteTime tm = GetCurrentTransactionStartTime();
    
    Assert(AbsoluteTimeIsValid(time1));
    Assert(AbsoluteTimeIsValid(time2));
    
    if ((time1 == CURRENT_ABSTIME) || (time2 == CURRENT_ABSTIME))
	return false;
    if (time1 == CURRENT_ABSTIME)
	return (tm > time2);
    if (time2 == CURRENT_ABSTIME)
	return (time1 > tm);
    
    return (time1 > time2);
}


/*
 *	abstimeeq	- returns 1, iff arguments are equal
 *	abstimene	- returns 1, iff arguments are not equal
 *	abstimelt	- returns 1, iff t1 less than t2
 *	abstimegt	- returns 1, iff t1 greater than t2
 *	abstimele	- returns 1, iff t1 less than or equal to t2
 *	abstimege	- returns 1, iff t1 greater than or equal to t2
 *
 */
int32
abstimeeq(AbsoluteTime t1, AbsoluteTime t2)
{
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	return 0;
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    if (t2 == CURRENT_ABSTIME)
	t2 = GetCurrentTransactionStartTime();
    
    return(t1 == t2);
}

int32
abstimene(AbsoluteTime t1, AbsoluteTime t2)
{ 
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	return 0;
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    if (t2 == CURRENT_ABSTIME)
	t2 = GetCurrentTransactionStartTime();
    
    return(t1 != t2);
}

int32
abstimelt(AbsoluteTime t1, AbsoluteTime t2)
{ 
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	return 0;
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    if (t2 == CURRENT_ABSTIME)
	t2 = GetCurrentTransactionStartTime();
    
    return(t1 < t2);
}

int32
abstimegt(AbsoluteTime t1, AbsoluteTime t2)
{ 
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	return 0;
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    if (t2 == CURRENT_ABSTIME)
	t2 = GetCurrentTransactionStartTime();
    
    return(t1 > t2);
}

int32
abstimele(AbsoluteTime t1, AbsoluteTime t2)
{ 
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	return 0;
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    if (t2 == CURRENT_ABSTIME)
	t2 = GetCurrentTransactionStartTime();
    
    return(t1 <= t2);
}

int32
abstimege(AbsoluteTime t1, AbsoluteTime t2)
{ 
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	return 0;
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    if (t2 == CURRENT_ABSTIME)
	t2 = GetCurrentTransactionStartTime();
    
    return(t1 >= t2);
}