datetime.h

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/*-------------------------------------------------------------------------
 *
 * datetime.h
 *    Definitions for date/time support code.
 *    The support code is shared with other date data types,
 *     including date, and time.
 *
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/utils/datetime.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef DATETIME_H
#define DATETIME_H

#include "nodes/nodes.h"
#include "utils/timestamp.h"

/* this struct is declared in utils/tzparser.h: */
struct tzEntry;


/* ----------------------------------------------------------------
 *              time types + support macros
 *
 * String definitions for standard time quantities.
 *
 * These strings are the defaults used to form output time strings.
 * Other alternative 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

/*
 * Field types 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.  Since those bits
 * are stored in typmods, you can't change them without initdb!
 */

#define RESERV  0
#define MONTH   1
#define YEAR    2
#define DAY     3
#define JULIAN  4
#define TZ      5               /* fixed-offset timezone abbreviation */
#define DTZ     6               /* fixed-offset timezone abbrev, DST */
#define DYNTZ   7               /* dynamic timezone abbreviation */
#define IGNORE_DTF  8
#define AMPM    9
#define HOUR    10
#define MINUTE  11
#define SECOND  12
#define MILLISECOND 13
#define MICROSECOND 14
#define DOY     15
#define DOW     16
#define UNITS   17
#define ADBC    18
/* these are only for relative dates */
#define AGO     19
#define ABS_BEFORE      20
#define ABS_AFTER       21
/* generic fields to help with parsing */
#define ISODATE 22
#define ISOTIME 23
/* these are only for parsing intervals */
#define WEEK        24
#define DECADE      25
#define CENTURY     26
#define MILLENNIUM  27
/* hack for parsing two-word timezone specs "MET DST" etc */
#define DTZMOD  28              /* "DST" as a separate word */
/* reserved for unrecognized string values */
#define UNKNOWN_FIELD   31

/*
 * Token field definitions for time parsing and decoding.
 *
 * Some field type codes (see above) use these as the "value" in datetktbl[].
 * These are also used for bit masks in DecodeDateTime and friends
 *  so actually restrict them to within [0,31] for now.
 * - thomas 97/06/19
 * Not all of these fields are used for masks in DecodeDateTime
 *  so allow some larger than 31. - thomas 1997-11-17
 *
 * Caution: there are undocumented assumptions in the code that most of these
 * values are not equal to IGNORE_DTF nor RESERV.  Be very careful when
 * renumbering values in either of these apparently-independent lists :-(
 */

#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_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
#define DTK_ISOYEAR     36
#define DTK_ISODOW      37


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

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

/* Convenience: a second, plus any fractional component */
#define DTK_ALL_SECS_M  (DTK_M(SECOND) | DTK_M(MILLISECOND) | DTK_M(MICROSECOND))
#define DTK_DATE_M      (DTK_M(YEAR) | DTK_M(MONTH) | DTK_M(DAY))
#define DTK_TIME_M      (DTK_M(HOUR) | DTK_M(MINUTE) | DTK_ALL_SECS_M)

/*
 * Working buffer size for input and output of interval, timestamp, etc.
 * Inputs that need more working space will be rejected early.  Longer outputs
 * will overrun buffers, so this must suffice for all possible output.  As of
 * this writing, interval_out() needs the most space at ~90 bytes.
 */
#define MAXDATELEN      128
/* maximum possible number of fields in a date string */
#define MAXDATEFIELDS   25
/* only this many chars are stored in datetktbl */
#define TOKMAXLEN       10

/* keep this struct small; it gets used a lot */
typedef struct
{
    char        token[TOKMAXLEN + 1];   /* always NUL-terminated */
    char        type;           /* see field type codes above */
    int32       value;          /* meaning depends on type */
} datetkn;

/* one of its uses is in tables of time zone abbreviations */
typedef struct TimeZoneAbbrevTable
{
    Size        tblsize;        /* size in bytes of TimeZoneAbbrevTable */
    int         numabbrevs;     /* number of entries in abbrevs[] array */
    datetkn     abbrevs[FLEXIBLE_ARRAY_MEMBER];
    /* DynamicZoneAbbrev(s) may follow the abbrevs[] array */
} TimeZoneAbbrevTable;

/* auxiliary data for a dynamic time zone abbreviation (non-fixed-offset) */
typedef struct DynamicZoneAbbrev
{
    pg_tz      *tz;             /* NULL if not yet looked up */
    char        zone[FLEXIBLE_ARRAY_MEMBER];    /* NUL-terminated zone name */
} DynamicZoneAbbrev;


/* 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 (now always int64).
 * We assume that int64 follows the C99 semantics for division (negative
 * quotients truncate towards zero).
 */
#define TMODULO(t,q,u) \
do { \
    (q) = ((t) / (u)); \
    if ((q) != 0) (t) -= ((q) * (u)); \
} while(0)

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

extern const char *const months[];  /* months (3-char abbreviations) */
extern const char *const days[];    /* days (full names) */
extern const int day_tab[2][13];

/*
 * These are the rules for the Gregorian calendar, which was adopted in 1582.
 * However, we use this calculation for all prior years as well because the
 * SQL standard specifies use of the Gregorian calendar.  This prevents the
 * date 1500-02-29 from being stored, even though it is valid in the Julian
 * calendar.
 */
#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))


/*
 * 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  DecodeTimezone(char *str, 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 range,
                           int *dtype, struct pg_tm *tm, fsec_t *fsec);
extern int  DecodeISO8601Interval(char *str,
                                  int *dtype, struct pg_tm *tm, fsec_t *fsec);

extern void DateTimeParseError(int dterr, const char *str,
                               const char *datatype) pg_attribute_noreturn();

extern int  DetermineTimeZoneOffset(struct pg_tm *tm, pg_tz *tzp);
extern int  DetermineTimeZoneAbbrevOffset(struct pg_tm *tm, const char *abbr, pg_tz *tzp);
extern int  DetermineTimeZoneAbbrevOffsetTS(TimestampTz ts, const char *abbr,
                                            pg_tz *tzp, int *isdst);

extern void EncodeDateOnly(struct pg_tm *tm, int style, char *str);
extern void EncodeTimeOnly(struct pg_tm *tm, fsec_t fsec, bool print_tz, int tz, int style, char *str);
extern void EncodeDateTime(struct pg_tm *tm, fsec_t fsec, bool print_tz, int tz, const char *tzn, int style, char *str);
extern void EncodeInterval(struct pg_tm *tm, fsec_t fsec, int style, char *str);
extern void EncodeSpecialTimestamp(Timestamp dt, char *str);

extern int  ValidateDate(int fmask, bool isjulian, bool is2digits, bool bc,
                         struct pg_tm *tm);

extern int  DecodeTimezoneAbbrev(int field, char *lowtoken,
                                 int *offset, pg_tz **tz);
extern int  DecodeSpecial(int field, char *lowtoken, int *val);
extern int  DecodeUnits(int field, char *lowtoken, int *val);

extern int  j2day(int jd);

extern Node *TemporalSimplify(int32 max_precis, Node *node);

extern bool CheckDateTokenTables(void);

extern TimeZoneAbbrevTable *ConvertTimeZoneAbbrevs(struct tzEntry *abbrevs,
                                                   int n);
extern void InstallTimeZoneAbbrevs(TimeZoneAbbrevTable *tbl);

extern void AdjustTimestampForTypmod(Timestamp *time, int32 typmod);
extern bool AdjustTimestampForTypmodError(Timestamp *time, int32 typmod,
                                          bool *error);

#endif                          /* DATETIME_H */