src/libpq/include/utils/datetime.h

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/*-------------------------------------------------------------------------
 *
 * datetime.h
 *        Definitions for the date/time and other date/time support code.
 *        The support code is shared with other date data types,
 *         including abstime, reltime, date, and time.
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/utils/datetime.h,v 1.57 2005/10/15 02:49:46 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef DATETIME_H
#define DATETIME_H

#include <limits.h>
#include <math.h>

#include "utils/timestamp.h"


/* ----------------------------------------------------------------
 *                              time types + support macros
 *
 * String definitions for standard time quantities.
 *
 * These strings are the defaults used to form output time strings.
 * Other alternate forms are hardcoded into token tables in datetime.c.
 * ----------------------------------------------------------------
 */

#define DAGO                    "ago"
#define DCURRENT                "current"
#define EPOCH                   "epoch"
#define INVALID                 "invalid"
#define EARLY                   "-infinity"
#define LATE                    "infinity"
#define NOW                             "now"
#define TODAY                   "today"
#define TOMORROW                "tomorrow"
#define YESTERDAY               "yesterday"
#define ZULU                    "zulu"

#define DMICROSEC               "usecond"
#define DMILLISEC               "msecond"
#define DSECOND                 "second"
#define DMINUTE                 "minute"
#define DHOUR                   "hour"
#define DDAY                    "day"
#define DWEEK                   "week"
#define DMONTH                  "month"
#define DQUARTER                "quarter"
#define DYEAR                   "year"
#define DDECADE                 "decade"
#define DCENTURY                "century"
#define DMILLENNIUM             "millennium"
#define DA_D                    "ad"
#define DB_C                    "bc"
#define DTIMEZONE               "timezone"

/*
 * Fundamental time field definitions for parsing.
 *
 *      Meridian:  am, pm, or 24-hour style.
 *      Millennium: ad, bc
 */

#define AM              0
#define PM              1
#define HR24    2

#define AD              0
#define BC              1

/*
 * Fields for time decoding.
 *
 * Can't have more of these than there are bits in an unsigned int
 * since these are turned into bit masks during parsing and decoding.
 *
 * Furthermore, the values for YEAR, MONTH, DAY, HOUR, MINUTE, SECOND
 * must be in the range 0..14 so that the associated bitmasks can fit
 * into the left half of an INTERVAL's typmod value.
 */

#define RESERV  0
#define MONTH   1
#define YEAR    2
#define DAY             3
#define JULIAN  4
#define TZ              5
#define DTZ             6
#define DTZMOD  7
#define IGNORE_DTF      8
#define AMPM    9
#define HOUR    10
#define MINUTE  11
#define SECOND  12
#define DOY             13
#define DOW             14
#define UNITS   15
#define ADBC    16
/* these are only for relative dates */
#define AGO             17
#define ABS_BEFORE              18
#define ABS_AFTER               19
/* generic fields to help with parsing */
#define ISODATE 20
#define ISOTIME 21
/* reserved for unrecognized string values */
#define UNKNOWN_FIELD   31

/*
 * Token field definitions for time parsing and decoding.
 * These need to fit into the datetkn table type.
 * At the moment, that means keep them within [-127,127].
 * These are also used for bit masks in DecodeDateDelta()
 *      so actually restrict them to within [0,31] for now.
 * - thomas 97/06/19
 * Not all of these fields are used for masks in DecodeDateDelta
 *      so allow some larger than 31. - thomas 1997-11-17
 */

#define DTK_NUMBER              0
#define DTK_STRING              1

#define DTK_DATE                2
#define DTK_TIME                3
#define DTK_TZ                  4
#define DTK_AGO                 5

#define DTK_SPECIAL             6
#define DTK_INVALID             7
#define DTK_CURRENT             8
#define DTK_EARLY               9
#define DTK_LATE                10
#define DTK_EPOCH               11
#define DTK_NOW                 12
#define DTK_YESTERDAY   13
#define DTK_TODAY               14
#define DTK_TOMORROW    15
#define DTK_ZULU                16

#define DTK_DELTA               17
#define DTK_SECOND              18
#define DTK_MINUTE              19
#define DTK_HOUR                20
#define DTK_DAY                 21
#define DTK_WEEK                22
#define DTK_MONTH               23
#define DTK_QUARTER             24
#define DTK_YEAR                25
#define DTK_DECADE              26
#define DTK_CENTURY             27
#define DTK_MILLENNIUM  28
#define DTK_MILLISEC    29
#define DTK_MICROSEC    30
#define DTK_JULIAN              31

#define DTK_DOW                 32
#define DTK_DOY                 33
#define DTK_TZ_HOUR             34
#define DTK_TZ_MINUTE   35


/*
 * Bit mask definitions for time parsing.
 */

#define DTK_M(t)                (0x01 << (t))

#define DTK_DATE_M              (DTK_M(YEAR) | DTK_M(MONTH) | DTK_M(DAY))
#define DTK_TIME_M              (DTK_M(HOUR) | DTK_M(MINUTE) | DTK_M(SECOND))

#define MAXDATELEN              51              /* maximum possible length of an input date
                                                                 * string (not counting tr. null) */
#define MAXDATEFIELDS   25              /* maximum possible number of fields in a date
                                                                 * string */
#define TOKMAXLEN               10              /* only this many chars are stored in
                                                                 * datetktbl */

/* keep this struct small; it gets used a lot */
typedef struct
{
#if defined(_AIX)
        char       *token;
#else
        char            token[TOKMAXLEN];
#endif   /* _AIX */
        char            type;
        char            value;                  /* this may be unsigned, alas */
} datetkn;


/* FMODULO()
 * Macro to replace modf(), which is broken on some platforms.
 * t = input and remainder
 * q = integer part
 * u = divisor
 */
#define FMODULO(t,q,u) \
do { \
        (q) = (((t) < 0) ? ceil((t) / (u)) : floor((t) / (u))); \
        if ((q) != 0) (t) -= rint((q) * (u)); \
} while(0)

/* TMODULO()
 * Like FMODULO(), but work on the timestamp datatype (either int64 or float8).
 * We assume that int64 follows the C99 semantics for division (negative
 * quotients truncate towards zero).
 */
#ifdef HAVE_INT64_TIMESTAMP
#define TMODULO(t,q,u) \
do { \
        (q) = ((t) / (u)); \
        if ((q) != 0) (t) -= ((q) * (u)); \
} while(0)
#else
#define TMODULO(t,q,u) \
do { \
        (q) = (((t) < 0) ? ceil((t) / (u)) : floor((t) / (u))); \
        if ((q) != 0) (t) -= rint((q) * (u)); \
} while(0)
#endif

/*
 * Date/time validation
 * Include check for leap year.
 */

extern const int day_tab[2][13];

#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))


/* Julian date support for date2j() and j2date()
 *
 * IS_VALID_JULIAN checks the minimum date exactly, but is a bit sloppy
 * about the maximum, since it's far enough out to not be especially
 * interesting.
 */

#define JULIAN_MINYEAR (-4713)
#define JULIAN_MINMONTH (11)
#define JULIAN_MINDAY (24)
#define JULIAN_MAXYEAR (5874898)

#define IS_VALID_JULIAN(y,m,d) ((((y) > JULIAN_MINYEAR) \
  || (((y) == JULIAN_MINYEAR) && (((m) > JULIAN_MINMONTH) \
  || (((m) == JULIAN_MINMONTH) && ((d) >= JULIAN_MINDAY))))) \
 && ((y) < JULIAN_MAXYEAR))

/* Julian-date equivalents of Day 0 in Unix and Postgres reckoning */
#define UNIX_EPOCH_JDATE                2440588 /* == date2j(1970, 1, 1) */
#define POSTGRES_EPOCH_JDATE    2451545 /* == date2j(2000, 1, 1) */


/*
 * Datetime input parsing routines (ParseDateTime, DecodeDateTime, etc)
 * return zero or a positive value on success.  On failure, they return
 * one of these negative code values.  DateTimeParseError may be used to
 * produce a correct ereport.
 */
#define DTERR_BAD_FORMAT                (-1)
#define DTERR_FIELD_OVERFLOW    (-2)
#define DTERR_MD_FIELD_OVERFLOW (-3)    /* triggers hint about DateStyle */
#define DTERR_INTERVAL_OVERFLOW (-4)
#define DTERR_TZDISP_OVERFLOW   (-5)


extern void GetCurrentDateTime(struct pg_tm * tm);
extern void GetCurrentTimeUsec(struct pg_tm * tm, fsec_t *fsec, int *tzp);
extern void j2date(int jd, int *year, int *month, int *day);
extern int      date2j(int year, int month, int day);

extern int ParseDateTime(const char *timestr, char *workbuf, size_t buflen,
                          char **field, int *ftype,
                          int maxfields, int *numfields);
extern int DecodeDateTime(char **field, int *ftype,
                           int nf, int *dtype,
                           struct pg_tm * tm, fsec_t *fsec, int *tzp);
extern int DecodeTimeOnly(char **field, int *ftype,
                           int nf, int *dtype,
                           struct pg_tm * tm, fsec_t *fsec, int *tzp);
extern int DecodeInterval(char **field, int *ftype,
                           int nf, int *dtype,
                           struct pg_tm * tm, fsec_t *fsec);
extern void DateTimeParseError(int dterr, const char *str,
                                   const char *datatype);

extern int      DetermineTimeZoneOffset(struct pg_tm * tm, pg_tz *tzp);

extern int      EncodeDateOnly(struct pg_tm * tm, int style, char *str);
extern int      EncodeTimeOnly(struct pg_tm * tm, fsec_t fsec, int *tzp, int style, char *str);
extern int      EncodeDateTime(struct pg_tm * tm, fsec_t fsec, int *tzp, char **tzn, int style, char *str);
extern int      EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str);

extern int      DecodeSpecial(int field, char *lowtoken, int *val);
extern int      DecodeUnits(int field, char *lowtoken, int *val);

extern int      j2day(int jd);

extern bool CheckDateTokenTables(void);

#endif   /* DATETIME_H */