pgsql/include/server/utils/datetime.h

/*-------------------------------------------------------------------------
 *
 * 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) 1996-2023, 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 "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 PGDLLIMPORT const char *const months[];	/* months (3-char
												 * abbreviations) */
extern PGDLLIMPORT const char *const days[];	/* days (full names) */
extern PGDLLIMPORT 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 suitable error report.  For some of these codes,
 * DateTimeParseError requires additional information, which is carried
 * in struct DateTimeErrorExtra.
 */
#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)
#define DTERR_BAD_TIMEZONE		(-6)
#define DTERR_BAD_ZONE_ABBREV	(-7)

typedef struct DateTimeErrorExtra
{
	/* Needed for DTERR_BAD_TIMEZONE and DTERR_BAD_ZONE_ABBREV: */
	const char *dtee_timezone;	/* incorrect time zone name */
	/* Needed for DTERR_BAD_ZONE_ABBREV: */
	const char *dtee_abbrev;	/* relevant time zone abbreviation */
} DateTimeErrorExtra;

/* Result codes for DecodeTimezoneName() */
#define TZNAME_FIXED_OFFSET	0
#define TZNAME_DYNTZ		1
#define TZNAME_ZONE			2


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,
						   DateTimeErrorExtra *extra);
extern int	DecodeTimezone(const char *str, int *tzp);
extern int	DecodeTimeOnly(char **field, int *ftype, int nf,
						   int *dtype, struct pg_tm *tm, fsec_t *fsec, int *tzp,
						   DateTimeErrorExtra *extra);
extern int	DecodeInterval(char **field, int *ftype, int nf, int range,
						   int *dtype, struct pg_itm_in *itm_in);
extern int	DecodeISO8601Interval(char *str,
								  int *dtype, struct pg_itm_in *itm_in);

extern void DateTimeParseError(int dterr, DateTimeErrorExtra *extra,
							   const char *str, const char *datatype,
							   struct Node *escontext);

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_itm *itm, 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, const char *lowtoken,
								 int *ftype, int *offset, pg_tz **tz,
								 DateTimeErrorExtra *extra);
extern int	DecodeSpecial(int field, const char *lowtoken, int *val);
extern int	DecodeUnits(int field, const char *lowtoken, int *val);

extern int	DecodeTimezoneName(const char *tzname, int *offset, pg_tz **tz);
extern pg_tz *DecodeTimezoneNameToTz(const char *tzname);

extern int	j2day(int date);

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

extern bool CheckDateTokenTables(void);

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

extern bool AdjustTimestampForTypmod(Timestamp *time, int32 typmod,
									 struct Node *escontext);

#endif							/* DATETIME_H */