parsedate.y

早期freebsd实现

    { "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 */