** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
-** $Id: func.c,v 1.27 2003/08/09 21:32:28 drh Exp $
+** $Id: func.c,v 1.28 2003/08/10 01:50:55 drh Exp $
*/
#include <ctype.h>
#include <math.h>
**
** SQLite processes all times and dates as Julian Day numbers. The
** dates and times are stored as the number of days since noon
-** in Greenwich on January 01, 4713 B.C. (a.k.a -4713-01-01 12:00:00)
+** in Greenwich on November 24, 4714 B.C. according to the Gregorian
+** calendar system.
+**
** This implement requires years to be expressed as a 4-digit number
** which means that only dates between 0000-01-01 and 9999-12-31 can
** be represented, even though julian day numbers allow a much wider
** range of dates.
**
** The Gregorian calendar system is used for all dates and times,
-** even those that predate the Gregorian calendar. Historians often
+** even those that predate the Gregorian calendar. Historians usually
** use the Julian calendar for dates prior to 1582-10-15 and for some
** dates afterwards, depending on locale. Beware of this difference.
**
}
/*
-** Parse dates of the form HH:MM:SS or HH:MM. Store the
+** Parse times of the form HH:MM:SS or HH:MM. Store the
** result (in days) in *prJD.
**
** Return 1 if there is a parsing error and 0 on success.
}
/*
-** Break up a julian day number into year, month, day, and seconds.
+** A structure for holding date and time.
+*/
+typedef struct DateTime DateTime;
+struct DateTime {
+ double rJD; /* The julian day number */
+ int Y, M, D; /* Year, month, and day */
+ int h, m, s; /* Hour minute and second */
+};
+
+/*
+** Break up a julian day number into year, month, day, hour, minute, second.
** This function assume the Gregorian calendar - even for dates prior
** to the invention of the Gregorian calendar in 1582.
**
** See Meeus page 63.
+**
+** If mode==1 only the year, month, and day are computed. If mode==2
+** then only the hour, minute, and second are computed. If mode==3 then
+** everything is computed. If mode==0, this routine is a no-op.
+*/
+static void decomposeDate(DateTime *p, int mode){
+ int Z;
+ Z = p->rJD + 0.5;
+ if( mode & 1 ){
+ int A, B, C, D, E, X1;
+ A = (Z - 1867216.25)/36524.25;
+ A = Z + 1 + A - (A/4);
+ B = A + 1524;
+ C = (B - 122.1)/365.25;
+ D = 365.25*C;
+ E = (B-D)/30.6001;
+ X1 = 30.6001*E;
+ p->D = B - D - X1;
+ p->M = E<14 ? E-1 : E-13;
+ p->Y = p->M>2 ? C - 4716 : C - 4715;
+ }
+ if( mode & 2 ){
+ p->s = (p->rJD + 0.5 - Z)*86400.0;
+ p->h = p->s/3600;
+ p->s -= p->h*3600;
+ p->m = p->s/60;
+ p->s -= p->m*60;
+ }
+}
+
+/*
+** Check to see that all arguments are valid date strings. If any
+** argument is not a valid date string, return 0. If all arguments
+** are valid, return 1 and write into *p->rJD the sum of the julian day
+** numbers for all date strings.
+**
+** A "valid" date string is one that is accepted by parseDateOrTime().
+**
+** The mode argument is passed through to decomposeDate() in order to
+** fill in the year, month, day, hour, minute, and second of the *p
+** structure, if desired.
*/
-static void decomposeDate(double JD, int *pY, int *pM, int *pD, int *pS){
- int Z, A, B, C, D, E, X1;
- Z = JD + 0.5;
- A = (Z - 1867216.25)/36524.25;
- A = Z + 1 + A - (A/4);
- B = A + 1524;
- C = (B - 122.1)/365.25;
- D = 365.25*C;
- E = (B-D)/30.6001;
- X1 = 30.6001*E;
- *pD = B - D - X1;
- *pM = E<14 ? E-1 : E-13;
- *pY = *pD>2 ? C - 4716 : C - 4715;
- *pS = (JD + 0.5 - Z)*86400.0;
-}
-
-/*
-** Check to see that all arguments are valid date strings. If any is
-** not a valid date string, return 0. If all are valid, return 1.
-** Write into *prJD the sum of the julian day numbers for all date
-** strings.
-*/
-static int isDate(
- sqlite_func *context,
- int argc,
- const char **argv,
- double *prJD
-){
+static int isDate(int argc, const char **argv, DateTime *p, int mode){
double r;
int i;
- *prJD = 0.0;
+ p->rJD = 0.0;
for(i=0; i<argc; i++){
if( argv[i]==0 ) return 0;
if( parseDateOrTime(argv[i], &r) ) return 0;
- *prJD += r;
+ p->rJD += r;
}
+ decomposeDate(p, mode);
return 1;
}
+
/*
** The following routines implement the various date and time functions
** of SQLite.
*/
static void juliandayFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- sqlite_set_result_double(context, JD);
+ DateTime x;
+ if( isDate(argc, argv, &x, 0) ){
+ sqlite_set_result_double(context, x.rJD);
}
}
static void timestampFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, h, m, s;
+ DateTime x;
+ if( isDate(argc, argv, &x, 3) ){
char zBuf[100];
- decomposeDate(JD, &Y, &M, &D, &s);
- h = s/3600;
- s -= h*3600;
- m = s/60;
- s -= m*60;
- sprintf(zBuf, "%04d-%02d-%02d %02d:%02d:%02d", Y, M, D, h, m, s);
+ sprintf(zBuf, "%04d-%02d-%02d %02d:%02d:%02d",x.Y, x.M, x.D, x.h, x.m, x.s);
sqlite_set_result_string(context, zBuf, -1);
}
}
static void timeFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, h, m, s;
+ DateTime x;
+ if( isDate(argc, argv, &x, 2) ){
char zBuf[100];
- decomposeDate(JD, &Y, &M, &D, &s);
- h = s/3600;
- s -= h*3600;
- m = s/60;
- s -= m*60;
- sprintf(zBuf, "%02d:%02d:%02d", h, m, s);
+ sprintf(zBuf, "%02d:%02d:%02d", x.h, x.m, x.s);
sqlite_set_result_string(context, zBuf, -1);
}
}
static void dateFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, s;
+ DateTime x;
+ if( isDate(argc, argv, &x, 1) ){
char zBuf[100];
- decomposeDate(JD, &Y, &M, &D, &s);
- sprintf(zBuf, "%04d-%02d-%02d", Y, M, D);
+ sprintf(zBuf, "%04d-%02d-%02d", x.Y, x.M, x.D);
sqlite_set_result_string(context, zBuf, -1);
}
}
static void yearFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, s;
- decomposeDate(JD, &Y, &M, &D, &s);
- sqlite_set_result_int(context, Y);
+ DateTime x;
+ if( isDate(argc, argv, &x, 1) ){
+ sqlite_set_result_int(context, x.Y);
}
}
static void monthFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, s;
- decomposeDate(JD, &Y, &M, &D, &s);
- sqlite_set_result_int(context, M);
+ DateTime x;
+ if( isDate(argc, argv, &x, 1) ){
+ sqlite_set_result_int(context, x.M);
}
}
static void dayofweekFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Z = JD + 1.5;
+ DateTime x;
+ if( isDate(argc, argv, &x, 0) ){
+ int Z = x.rJD + 1.5;
sqlite_set_result_int(context, Z % 7);
}
}
static void dayofmonthFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, s;
- decomposeDate(JD, &Y, &M, &D, &s);
- sqlite_set_result_int(context, D);
+ DateTime x;
+ if( isDate(argc, argv, &x, 1) ){
+ sqlite_set_result_int(context, x.D);
}
}
static void secondFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, h, m, s;
- decomposeDate(JD, &Y, &M, &D, &s);
- h = s/3600;
- s -= h*3600;
- m = s/60;
- s -= m*60;
- sqlite_set_result_int(context, s);
+ DateTime x;
+ if( isDate(argc, argv, &x, 2) ){
+ sqlite_set_result_int(context, x.s);
}
}
static void minuteFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, h, m, s;
- decomposeDate(JD, &Y, &M, &D, &s);
- h = s/3600;
- s -= h*3600;
- m = s/60;
- sqlite_set_result_int(context, m);
+ DateTime x;
+ if( isDate(argc, argv, &x, 2) ){
+ sqlite_set_result_int(context, x.m);
}
}
static void hourFunc(sqlite_func *context, int argc, const char **argv){
- double JD;
- if( isDate(context, argc, argv, &JD) ){
- int Y, M, D, h, s;
- decomposeDate(JD, &Y, &M, &D, &s);
- h = s/3600;
- sqlite_set_result_int(context, h);
+ DateTime x;
+ if( isDate(argc, argv, &x, 2) ){
+ sqlite_set_result_int(context, x.h);
}
}
#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */
projects / thirdparty / sqlite.git / commitdiff
