SQLite

** This file contains the C functions that implement date and time
** functions for SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterDateTimeFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: date.c,v 1.3 2003/12/23 16:22:18 drh Exp $
**
** NOTES:
**
** 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 November 24, 4714 B.C. according to the Gregorian
** calendar system.

**      Willmann-Bell, Inc
**      Richmond, Virginia (USA)
*/
#ifndef SQLITE_OMIT_DATETIME_FUNCS
#include <ctype.h>
#include <stdlib.h>
#include <assert.h>
#include <time.h>
#include "sqliteInt.h"
#include "os.h"

/*
** A structure for holding a single date and time.
*/
typedef struct DateTime DateTime;

  p->s -= s;
  p->h = s/3600;
  s -= p->h*3600;
  p->m = s/60;
  p->s += s - p->m*60;
  p->validHMS = 1;
}

/*
** Compute the difference (in days) between localtime and UTC (a.k.a. GMT)
** for the time value p where p is in UTC.
*/
static double localtimeOffset(DateTime *p){
  DateTime x, y;
  time_t t;
  struct tm *pTm;
  computeYMD(p);
  computeHMS(p);
  x = *p;
  if( x.Y<1971 || x.Y>=2038 ){
    x.Y = 2000;
    x.M = 1;
    x.D = 1;
    x.h = 0;
    x.m = 0;
    x.s = 0.0;
  } else {
    int s = x.s + 0.5;
    x.s = s;
  }
  x.tz = 0;
  x.validJD = 0;
  computeJD(&x);
  t = (x.rJD-2440587.5)*86400.0 + 0.5;
  sqliteOsEnterMutex();
  pTm = localtime(&t);
  y.Y = pTm->tm_year + 1900;
  y.M = pTm->tm_mon + 1;
  y.D = pTm->tm_mday;
  y.h = pTm->tm_hour;
  y.m = pTm->tm_min;
  y.s = pTm->tm_sec;
  sqliteOsLeaveMutex();
  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.validTZ = 0;
  computeJD(&y);
  /* printf("x=%d-%02d-%02d %02d:%02d:%02d\n",x.Y,x.M,x.D,x.h,x.m,(int)x.s); */
  /* printf("y=%d-%02d-%02d %02d:%02d:%02d\n",y.Y,y.M,y.D,y.h,y.m,(int)y.s); */
  /* printf("diff=%.17g\n", y.rJD - x.rJD); */
  return y.rJD - x.rJD;
}

/*
** Process a modifier to a date-time stamp.  The modifiers are
** as follows:
**
**     NNN days
**     NNN hours
**     NNN minutes
**     NNN.NNNN seconds
**     NNN months
**     NNN years
**     start of month
**     start of year
**     start of week
**     start of day
**     weekday N
**     unixepoch
**     localtime
**     utc
**
** Return 0 on success and 1 if there is any kind of error.
*/
static int parseModifier(const char *zMod, DateTime *p){
  int rc = 1;
  int n;
  double r;
  char z[30];
  for(n=0; n<sizeof(z)-1; n++){
    z[n] = tolower(zMod[n]);
  }
  z[n] = 0;
  switch( z[0] ){
    case 'l': {
      /*    localtime
      **
      ** Assuming the current time value is UTC (a.k.a. GMT), shift it to
      ** show local time.
      */
      if( strcmp(z, "localtime")==0 ){
        computeJD(p);
        p->rJD += localtimeOffset(p);
        p->validYMD = 0;
        p->validHMS = 0;
        p->validTZ = 0;
        rc = 0;
      }
      break;
    }
    case 'u': {
      /*
      **    unixepoch
      **
      ** Treat the current value of p->rJD as the number of
      ** seconds since 1970.  Convert to a real julian day number.
      */
      if( strcmp(z, "unixepoch")==0 && p->validJD ){
        p->rJD = p->rJD/86400.0 + 2440587.5;
        p->validYMD = 0;
        p->validHMS = 0;
        p->validTZ = 0;
        rc = 0;
      }else if( strcmp(z, "utc")==0 ){
        double c1;
        computeJD(p);
        c1 = localtimeOffset(p);
        p->rJD -= c1;
        p->validYMD = 0;
        p->validHMS = 0;
        p->validTZ = 0;
        p->rJD += c1 - localtimeOffset(p);
        p->validYMD = 0;
        p->validHMS = 0;
        p->validTZ = 0;
        rc = 0;
      }
      break;
    }
    case 'w': {
      /*
      **    weekday N

# 2003 October 31
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing date and time functions.
#
# $Id: date.test,v 1.2 2003/12/23 16:22:18 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

proc datetest {tnum expr result} {
  do_test date-$tnum [subst {
    execsql "SELECT coalesce($expr,'NULL')"

set now [clock format [clock seconds] -format "%Y-%m-%d" -gmt 1]
datetest 4.1 {date('now')} $now

datetest 5.1 {datetime('1994-04-16 14:00:00 -05:00')} {1994-04-16 09:00:00}
datetest 5.2 {datetime('1994-04-16 14:00:00 +05:15')} {1994-04-16 19:15:00}
datetest 5.3 {datetime('1994-04-16 05:00:00 -08:30')} {1994-04-15 20:30:00}
datetest 5.4 {datetime('1994-04-16 14:00:00 +11:55')} {1994-04-17 01:55:00}

# localtime->utc and utc->localtime conversions.  These tests only work
# if the localtime is in the US Eastern Time (the time in Charlotte, NC
# and in New York.)
#
if {[clock format 0 -format %Z]=="EST"} {
  datetest 6.1 {datetime('2000-10-29 05:59:00','localtime')}\
      {2000-10-29 01:59:00}
  datetest 6.2 {datetime('2000-10-29 06:00:00','localtime')}\
      {2000-10-29 01:00:00}
  datetest 6.3 {datetime('2000-04-02 06:59:00','localtime')}\
      {2000-04-02 01:59:00}
  datetest 6.4 {datetime('2000-04-02 07:00:00','localtime')}\
      {2000-04-02 03:00:00}
  datetest 6.5 {datetime('2000-10-29 01:59:00','utc')} {2000-10-29 05:59:00}
  datetest 6.6 {datetime('2000-10-29 02:00:00','utc')} {2000-10-29 07:00:00}
  datetest 6.7 {datetime('2000-04-02 01:59:00','utc')} {2000-04-02 06:59:00}
  datetest 6.8 {datetime('2000-04-02 02:00:00','utc')} {2000-04-02 06:00:00}

  datetest 6.10 {datetime('2000-01-01 12:00:00','localtime')} \
      {2000-01-01 07:00:00}
  datetest 6.11 {datetime('1969-01-01 12:00:00','localtime')} \
      {1969-01-01 07:00:00}
  datetest 6.12 {datetime('2039-01-01 12:00:00','localtime')} \
      {2039-01-01 07:00:00}
  datetest 6.13 {datetime('2000-07-01 12:00:00','localtime')} \
      {2000-07-01 08:00:00}
  datetest 6.14 {datetime('1969-07-01 12:00:00','localtime')} \
      {1969-07-01 07:00:00}
  datetest 6.15 {datetime('2039-07-01 12:00:00','localtime')} \
      {2039-07-01 07:00:00}
}

finish_test