datetime.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/* Used for SET australian_timezones to override North American ones */
static datetkn australian_datetktbl[] = {
	{"acst", TZ, POS(38)},		/* Cent. Australia */
	{"cst", TZ, POS(42)},		/* Australia Central Std Time */
	{"east", TZ, POS(40)},		/* East Australian Std Time */
	{"est", TZ, POS(40)},		/* Australia Eastern Std Time */
	{"sat", TZ, POS(38)},
};

static unsigned int australian_szdatetktbl = sizeof australian_datetktbl /
sizeof australian_datetktbl[0];

static datetkn deltatktbl[] = {
	/* text, token, lexval */
	{"@", IGNORE_DTF, 0},		/* postgres relative prefix */
	{DAGO, AGO, 0},				/* "ago" indicates negative time offset */
	{"c", UNITS, DTK_CENTURY},	/* "century" relative */
	{"cent", UNITS, DTK_CENTURY},		/* "century" relative */
	{"centuries", UNITS, DTK_CENTURY},	/* "centuries" relative */
	{DCENTURY, UNITS, DTK_CENTURY},		/* "century" relative */
	{"d", UNITS, DTK_DAY},		/* "day" relative */
	{DDAY, UNITS, DTK_DAY},		/* "day" relative */
	{"days", UNITS, DTK_DAY},	/* "days" relative */
	{"dec", UNITS, DTK_DECADE}, /* "decade" relative */
	{DDECADE, UNITS, DTK_DECADE},		/* "decade" relative */
	{"decades", UNITS, DTK_DECADE},		/* "decades" relative */
	{"decs", UNITS, DTK_DECADE},	/* "decades" relative */
	{"h", UNITS, DTK_HOUR},		/* "hour" relative */
	{DHOUR, UNITS, DTK_HOUR},	/* "hour" relative */
	{"hours", UNITS, DTK_HOUR}, /* "hours" relative */
	{"hr", UNITS, DTK_HOUR},	/* "hour" relative */
	{"hrs", UNITS, DTK_HOUR},	/* "hours" relative */
	{INVALID, RESERV, DTK_INVALID},		/* reserved for invalid time */
	{"m", UNITS, DTK_MINUTE},	/* "minute" relative */
	{"microsecon", UNITS, DTK_MICROSEC},		/* "microsecond" relative */
	{"mil", UNITS, DTK_MILLENNIUM},		/* "millennium" relative */
	{"millennia", UNITS, DTK_MILLENNIUM},		/* "millennia" relative */
	{DMILLENNIUM, UNITS, DTK_MILLENNIUM},		/* "millennium" relative */
	{"millisecon", UNITS, DTK_MILLISEC},		/* relative */
	{"mils", UNITS, DTK_MILLENNIUM},	/* "millennia" relative */
	{"min", UNITS, DTK_MINUTE}, /* "minute" relative */
	{"mins", UNITS, DTK_MINUTE},	/* "minutes" relative */
	{DMINUTE, UNITS, DTK_MINUTE},		/* "minute" relative */
	{"minutes", UNITS, DTK_MINUTE},		/* "minutes" relative */
	{"mon", UNITS, DTK_MONTH},	/* "months" relative */
	{"mons", UNITS, DTK_MONTH}, /* "months" relative */
	{DMONTH, UNITS, DTK_MONTH}, /* "month" relative */
	{"months", UNITS, DTK_MONTH},
	{"ms", UNITS, DTK_MILLISEC},
	{"msec", UNITS, DTK_MILLISEC},
	{DMILLISEC, UNITS, DTK_MILLISEC},
	{"mseconds", UNITS, DTK_MILLISEC},
	{"msecs", UNITS, DTK_MILLISEC},
	{"qtr", UNITS, DTK_QUARTER},	/* "quarter" relative */
	{DQUARTER, UNITS, DTK_QUARTER},		/* "quarter" relative */
	{"reltime", IGNORE_DTF, 0}, /* pre-v6.1 "Undefined Reltime" */
	{"s", UNITS, DTK_SECOND},
	{"sec", UNITS, DTK_SECOND},
	{DSECOND, UNITS, DTK_SECOND},
	{"seconds", UNITS, DTK_SECOND},
	{"secs", UNITS, DTK_SECOND},
	{DTIMEZONE, UNITS, DTK_TZ}, /* "timezone" time offset */
	{"timezone_h", UNITS, DTK_TZ_HOUR}, /* timezone hour units */
	{"timezone_m", UNITS, DTK_TZ_MINUTE},		/* timezone minutes units */
	{"undefined", RESERV, DTK_INVALID}, /* pre-v6.1 invalid time */
	{"us", UNITS, DTK_MICROSEC},	/* "microsecond" relative */
	{"usec", UNITS, DTK_MICROSEC},		/* "microsecond" relative */
	{DMICROSEC, UNITS, DTK_MICROSEC},	/* "microsecond" relative */
	{"useconds", UNITS, DTK_MICROSEC},	/* "microseconds" relative */
	{"usecs", UNITS, DTK_MICROSEC},		/* "microseconds" relative */
	{"w", UNITS, DTK_WEEK},		/* "week" relative */
	{DWEEK, UNITS, DTK_WEEK},	/* "week" relative */
	{"weeks", UNITS, DTK_WEEK}, /* "weeks" relative */
	{"y", UNITS, DTK_YEAR},		/* "year" relative */
	{DYEAR, UNITS, DTK_YEAR},	/* "year" relative */
	{"years", UNITS, DTK_YEAR}, /* "years" relative */
	{"yr", UNITS, DTK_YEAR},	/* "year" relative */
	{"yrs", UNITS, DTK_YEAR},	/* "years" relative */
};

static unsigned int szdeltatktbl = sizeof deltatktbl / sizeof deltatktbl[0];

static datetkn *datecache[MAXDATEFIELDS] = {NULL};

static datetkn *deltacache[MAXDATEFIELDS] = {NULL};


/*
 * Calendar time to Julian date conversions.
 * Julian date is commonly used in astronomical applications,
 *	since it is numerically accurate and computationally simple.
 * The algorithms here will accurately convert between Julian day
 *	and calendar date for all non-negative Julian days
 *	(i.e. from Nov 24, -4713 on).
 *
 * These routines will be used by other date/time packages
 * - thomas 97/02/25
 *
 * Rewritten to eliminate overflow problems. This now allows the
 * routines to work correctly for all Julian day counts from
 * 0 to 2147483647	(Nov 24, -4713 to Jun 3, 5874898) assuming
 * a 32-bit integer. Longer types should also work to the limits
 * of their precision.
 */

int
date2j(int y, int m, int d)
{
	int			julian;
	int			century;

	if (m > 2)
	{
		m += 1;
		y += 4800;
	}
	else
	{
		m += 13;
		y += 4799;
	}

	century = y / 100;
	julian = y * 365 - 32167;
	julian += y / 4 - century + century / 4;
	julian += 7834 * m / 256 + d;

	return julian;
}	/* date2j() */

void
j2date(int jd, int *year, int *month, int *day)
{
	unsigned int julian;
	unsigned int quad;
	unsigned int extra;
	int			y;

	julian = jd;
	julian += 32044;
	quad = julian / 146097;
	extra = (julian - quad * 146097) * 4 + 3;
	julian += 60 + quad * 3 + extra / 146097;
	quad = julian / 1461;
	julian -= quad * 1461;
	y = julian * 4 / 1461;
	julian = ((y != 0) ? ((julian + 305) % 365) : ((julian + 306) % 366))
		+ 123;
	y += quad * 4;
	*year = y - 4800;
	quad = julian * 2141 / 65536;
	*day = julian - 7834 * quad / 256;
	*month = (quad + 10) % 12 + 1;

	return;
}	/* j2date() */


/*
 * j2day - convert Julian date to day-of-week (0..6 == Sun..Sat)
 *
 * Note: various places use the locution j2day(date - 1) to produce a
 * result according to the convention 0..6 = Mon..Sun.	This is a bit of
 * a crock, but will work as long as the computation here is just a modulo.
 */
int
j2day(int date)
{
	unsigned int day;

	day = date;

	day += 1;
	day %= 7;

	return (int) day;
}	/* j2day() */


/*
 * GetCurrentDateTime()
 *
 * Get the transaction start time ("now()") broken down as a struct pg_tm.
 */
void
GetCurrentDateTime(struct pg_tm * tm)
{
	int			tz;
	fsec_t		fsec;

	timestamp2tm(GetCurrentTransactionStartTimestamp(), &tz, tm, &fsec,
				 NULL, NULL);
	/* Note: don't pass NULL tzp to timestamp2tm; affects behavior */
}

/*
 * GetCurrentTimeUsec()
 *
 * Get the transaction start time ("now()") broken down as a struct pg_tm,
 * including fractional seconds and timezone offset.
 */
void
GetCurrentTimeUsec(struct pg_tm * tm, fsec_t *fsec, int *tzp)
{
	int			tz;

	timestamp2tm(GetCurrentTransactionStartTimestamp(), &tz, tm, fsec,
				 NULL, NULL);
	/* Note: don't pass NULL tzp to timestamp2tm; affects behavior */
	if (tzp != NULL)
		*tzp = tz;
}


/* TrimTrailingZeros()
 * ... resulting from printing numbers with full precision.
 */
static void
TrimTrailingZeros(char *str)
{
	int			len = strlen(str);

#if 0
	/* chop off trailing one to cope with interval rounding */
	if (strcmp(str + len - 4, "0001") == 0)
	{
		len -= 4;
		*(str + len) = '\0';
	}
#endif

	/* chop off trailing zeros... but leave at least 2 fractional digits */
	while (*(str + len - 1) == '0' && *(str + len - 3) != '.')
	{
		len--;
		*(str + len) = '\0';
	}
}

/* ParseDateTime()
 *	Break string into tokens based on a date/time context.
 *	Returns 0 if successful, DTERR code if bogus input detected.
 *
 * timestr - the input string
 * workbuf - workspace for field string storage. This must be
 *	 larger than the largest legal input for this datetime type --
 *	 some additional space will be needed to NUL terminate fields.
 * buflen - the size of workbuf
 * field[] - pointers to field strings are returned in this array
 * ftype[] - field type indicators are returned in this array
 * maxfields - dimensions of the above two arrays
 * *numfields - set to the actual number of fields detected
 *
 * The fields extracted from the input are stored as separate,
 * null-terminated strings in the workspace at workbuf. Any text is
 * converted to lower case.
 *
 * Several field types are assigned:
 *	DTK_NUMBER - digits and (possibly) a decimal point
 *	DTK_DATE - digits and two delimiters, or digits and text
 *	DTK_TIME - digits, colon delimiters, and possibly a decimal point
 *	DTK_STRING - text (no digits)
 *	DTK_SPECIAL - leading "+" or "-" followed by text
 *	DTK_TZ - leading "+" or "-" followed by digits
 *
 * Note that some field types can hold unexpected items:
 *	DTK_NUMBER can hold date fields (yy.ddd)
 *	DTK_STRING can hold months (January) and time zones (PST)
 *	DTK_DATE can hold Posix time zones (GMT-8)
 */
int
ParseDateTime(const char *timestr, char *workbuf, size_t buflen,
			  char **field, int *ftype, int maxfields, int *numfields)
{
	int			nf = 0;
	const char *cp = timestr;
	char	   *bufp = workbuf;
	const char *bufend = workbuf + buflen;

	/*
	 * Set the character pointed-to by "bufptr" to "newchar", and increment
	 * "bufptr". "end" gives the end of the buffer -- we return an error if
	 * there is no space left to append a character to the buffer. Note that
	 * "bufptr" is evaluated twice.
	 */
#define APPEND_CHAR(bufptr, end, newchar)		\
	do											\
	{											\
		if (((bufptr) + 1) >= (end))			\
			return DTERR_BAD_FORMAT;			\
		*(bufptr)++ = newchar;					\
	} while (0)

	/* outer loop through fields */
	while (*cp != '\0')
	{
		/* Ignore spaces between fields */
		if (isspace((unsigned char) *cp))
		{
			cp++;
			continue;
		}

		/* Record start of current field */
		if (nf >= maxfields)
			return DTERR_BAD_FORMAT;
		field[nf] = bufp;

		/* leading digit? then date or time */
		if (isdigit((unsigned char) *cp))
		{
			APPEND_CHAR(bufp, bufend, *cp++);
			while (isdigit((unsigned char) *cp))
				APPEND_CHAR(bufp, bufend, *cp++);

			/* time field? */
			if (*cp == ':')
			{
				ftype[nf] = DTK_TIME;
				APPEND_CHAR(bufp, bufend, *cp++);
				while (isdigit((unsigned char) *cp) ||
					   (*cp == ':') || (*cp == '.'))
					APPEND_CHAR(bufp, bufend, *cp++);
			}
			/* date field? allow embedded text month */
			else if (*cp == '-' || *cp == '/' || *cp == '.')
			{
				/* save delimiting character to use later */
				char		delim = *cp;

				APPEND_CHAR(bufp, bufend, *cp++);
				/* second field is all digits? then no embedded text month */
				if (isdigit((unsigned char) *cp))
				{
					ftype[nf] = ((delim == '.') ? DTK_NUMBER : DTK_DATE);
					while (isdigit((unsigned char) *cp))
						APPEND_CHAR(bufp, bufend, *cp++);

					/*
					 * insist that the delimiters match to get a three-field
					 * date.
					 */
					if (*cp == delim)
					{
						ftype[nf] = DTK_DATE;
						APPEND_CHAR(bufp, bufend, *cp++);
						while (isdigit((unsigned char) *cp) || *cp == delim)
							APPEND_CHAR(bufp, bufend, *cp++);
					}
				}
				else
				{
					ftype[nf] = DTK_DATE;
					while (isalnum((unsigned char) *cp) || *cp == delim)
						APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
				}
			}

			/*
			 * otherwise, number only and will determine year, month, day, or
			 * concatenated fields later...
			 */
			else
				ftype[nf] = DTK_NUMBER;
		}
		/* Leading decimal point? Then fractional seconds... */
		else if (*cp == '.')
		{
			APPEND_CHAR(bufp, bufend, *cp++);
			while (isdigit((unsigned char) *cp))
				APPEND_CHAR(bufp, bufend, *cp++);

			ftype[nf] = DTK_NUMBER;
		}

		/*
		 * text? then date string, month, day of week, special, or timezone
		 */
		else if (isalpha((unsigned char) *cp))
		{
			ftype[nf] = DTK_STRING;
			APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
			while (isalpha((unsigned char) *cp))
				APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));

			/*
			 * Full date string with leading text month? Could also be a POSIX
			 * time zone...
			 */
			if (*cp == '-' || *cp == '/' || *cp == '.')
			{
				char		delim = *cp;

				ftype[nf] = DTK_DATE;
				APPEND_CHAR(bufp, bufend, *cp++);
				while (isdigit((unsigned char) *cp) || *cp == delim)
					APPEND_CHAR(bufp, bufend, *cp++);
			}
		}
		/* sign? then special or numeric timezone */
		else if (*cp == '+' || *cp == '-')
		{
			APPEND_CHAR(bufp, bufend, *cp++);
			/* soak up leading whitespace */
			while (isspace((unsigned char) *cp))
				cp++;
			/* numeric timezone? */
			if (isdigit((unsigned char) *cp))
			{
				ftype[nf] = DTK_TZ;
				APPEND_CHAR(bufp, bufend, *cp++);
				while (isdigit((unsigned char) *cp) ||
					   *cp == ':' || *cp == '.')
					APPEND_CHAR(bufp, bufend, *cp++);
			}
			/* special? */
			else if (isalpha((unsigned char) *cp))
			{
				ftype[nf] = DTK_SPECIAL;
				APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
				while (isalpha((unsigned char) *cp))
					APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
			}
			/* otherwise something wrong... */
			else
				return DTERR_BAD_FORMAT;
		}
		/* ignore other punctuation but use as delimiter */
		else if (ispunct((unsigned char) *cp))
		{
			cp++;
			continue;
		}
		/* otherwise, something is not right... */
		else
			return DTERR_BAD_FORMAT;

		/* force in a delimiter after each field */
		*bufp++ = '\0';
		nf++;
	}

	*numfields = nf;

	return 0;
}


/* DecodeDateTime()
 * Interpret previously parsed fields for general date and time.
 * Return 0 if full date, 1 if only time, and negative DTERR code if problems.
 * (Currently, all callers treat 1 as an error return too.)
 *
 *		External format(s):
 *				"<weekday> <month>-<day>-<year> <hour>:<minute>:<second>"
 *				"Fri Feb-7-1997 15:23:27"
 *				"Feb-7-1997 15:23:27"
 *				"2-7-1997 15:23:27"
 *				"1997-2-7 15:23:27"
 *				"1997.038 15:23:27"		(day of year 1-366)
 *		Also supports input in compact time:
 *				"970207 152327"
 *				"97038 152327"
 *				"20011225T040506.789-07"
 *
 * Use the system-provided functions to get the current time zone
 *	if not specified in the input string.
 * If the date is outside the time_t system-supported time range,
 *	then assume UTC time zone. - thomas 1997-05-27
 */
int
DecodeDateTime(char **field, int *ftype, int nf,
			   int *dtype, struct pg_tm * tm, fsec_t *fsec, int *tzp)
{
	int			fmask = 0,
				tmask,
				type;
	int			ptype = 0;		/* "prefix type" for ISO y2001m02d04 format */
	int			i;
	int			val;
	int			dterr;
	int			mer = HR24;
	bool		haveTextMonth = FALSE;
	int			is2digits = FALSE;
	int			bc = FALSE;

	/*
	 * We'll insist on at least all of the date fields, but initialize the
	 * remaining fields in case they are not set later...
	 */
	*dtype = DTK_DATE;
	tm->tm_hour = 0;
	tm->tm_min = 0;
	tm->tm_sec = 0;
	*fsec = 0;