engine/sqlite/src/date.cpp
changeset 71 fbd95db6a4e1
parent 69 4a65cc85c4f3
child 72 2e267e7da513
--- a/engine/sqlite/src/date.cpp	Wed Apr 28 13:20:05 2010 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1045 +0,0 @@
-/*
-** 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 contains the C functions that implement date and time
-** functions for SQLite.  
-**
-** There is only one exported symbol in this file - the function
-** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
-** All other code has file scope.
-**
-** $Id: date.cpp 1282 2008-11-13 09:31:33Z LarsPson $
-**
-** 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. 
-**
-** 1970-01-01 00:00:00 is JD 2440587.5
-** 2000-01-01 00:00:00 is JD 2451544.5
-**
-** This implemention 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 usually
-** use the Julian calendar for dates prior to 1582-10-15 and for some
-** dates afterwards, depending on locale.  Beware of this difference.
-**
-** The conversion algorithms are implemented based on descriptions
-** in the following text:
-**
-**      Jean Meeus
-**      Astronomical Algorithms, 2nd Edition, 1998
-**      ISBM 0-943396-61-1
-**      Willmann-Bell, Inc
-**      Richmond, Virginia (USA)
-*/
-#include "sqliteInt.h"
-#include <ctype.h>
-#include <stdlib.h>
-#include <assert.h>
-#include <time.h>
-
-#ifndef SQLITE_OMIT_DATETIME_FUNCS
-
-/*
-** A structure for holding a single 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;        /* Hour and minutes */
-  int tz;          /* Timezone offset in minutes */
-  double s;        /* Seconds */
-  char validYMD;   /* True if Y,M,D are valid */
-  char validHMS;   /* True if h,m,s are valid */
-  char validJD;    /* True if rJD is valid */
-  char validTZ;    /* True if tz is valid */
-};
-
-
-/*
-** Convert zDate into one or more integers.  Additional arguments
-** come in groups of 5 as follows:
-**
-**       N       number of digits in the integer
-**       min     minimum allowed value of the integer
-**       max     maximum allowed value of the integer
-**       nextC   first character after the integer
-**       pVal    where to write the integers value.
-**
-** Conversions continue until one with nextC==0 is encountered.
-** The function returns the number of successful conversions.
-*/
-static int getDigits(const char *zDate, ...){
-  va_list ap;
-  int val;
-  int N;
-  int min;
-  int max;
-  int nextC;
-  int *pVal;
-  int cnt = 0;
-  va_start(ap, zDate);
-  do{
-    N = va_arg(ap, int);
-    min = va_arg(ap, int);
-    max = va_arg(ap, int);
-    nextC = va_arg(ap, int);
-    pVal = va_arg(ap, int*);
-    val = 0;
-    while( N-- ){
-      if( !isdigit(*(u8*)zDate) ){
-        goto end_getDigits;
-      }
-      val = val*10 + *zDate - '0';
-      zDate++;
-    }
-    if( val<min || val>max || (nextC!=0 && nextC!=*zDate) ){
-      goto end_getDigits;
-    }
-    *pVal = val;
-    zDate++;
-    cnt++;
-  }while( nextC );
-end_getDigits:
-  va_end(ap);
-  return cnt;
-}
-
-/*
-** Read text from z[] and convert into a floating point number.  Return
-** the number of digits converted.
-*/
-#define getValue sqlite3AtoF
-
-/*
-** Parse a timezone extension on the end of a date-time.
-** The extension is of the form:
-**
-**        (+/-)HH:MM
-**
-** If the parse is successful, write the number of minutes
-** of change in *pnMin and return 0.  If a parser error occurs,
-** return 0.
-**
-** A missing specifier is not considered an error.
-*/
-static int parseTimezone(const char *zDate, DateTime *p){
-  int sgn = 0;
-  int nHr, nMn;
-  while( isspace(*(u8*)zDate) ){ zDate++; }
-  p->tz = 0;
-  if( *zDate=='-' ){
-    sgn = -1;
-  }else if( *zDate=='+' ){
-    sgn = +1;
-  }else{
-    return *zDate!=0;
-  }
-  zDate++;
-  if( getDigits(zDate, 2, 0, 14, ':', &nHr, 2, 0, 59, 0, &nMn)!=2 ){
-    return 1;
-  }
-  zDate += 5;
-  p->tz = sgn*(nMn + nHr*60);
-  while( isspace(*(u8*)zDate) ){ zDate++; }
-  return *zDate!=0;
-}
-
-/*
-** Parse times of the form HH:MM or HH:MM:SS or HH:MM:SS.FFFF.
-** The HH, MM, and SS must each be exactly 2 digits.  The
-** fractional seconds FFFF can be one or more digits.
-**
-** Return 1 if there is a parsing error and 0 on success.
-*/
-static int parseHhMmSs(const char *zDate, DateTime *p){
-  int h, m, s;
-  double ms = 0.0;
-  if( getDigits(zDate, 2, 0, 24, ':', &h, 2, 0, 59, 0, &m)!=2 ){
-    return 1;
-  }
-  zDate += 5;
-  if( *zDate==':' ){
-    zDate++;
-    if( getDigits(zDate, 2, 0, 59, 0, &s)!=1 ){
-      return 1;
-    }
-    zDate += 2;
-    if( *zDate=='.' && isdigit((u8)zDate[1]) ){
-      double rScale = 1.0;
-      zDate++;
-      while( isdigit(*(u8*)zDate) ){
-        ms = ms*10.0 + *zDate - '0';
-        rScale *= 10.0;
-        zDate++;
-      }
-      ms /= rScale;
-    }
-  }else{
-    s = 0;
-  }
-  p->validJD = 0;
-  p->validHMS = 1;
-  p->h = h;
-  p->m = m;
-  p->s = s + ms;
-  if( parseTimezone(zDate, p) ) return 1;
-  p->validTZ = p->tz!=0;
-  return 0;
-}
-
-/*
-** Convert from YYYY-MM-DD HH:MM:SS to julian day.  We always assume
-** that the YYYY-MM-DD is according to the Gregorian calendar.
-**
-** Reference:  Meeus page 61
-*/
-static void computeJD(DateTime *p){
-  int Y, M, D, A, B, X1, X2;
-
-  if( p->validJD ) return;
-  if( p->validYMD ){
-    Y = p->Y;
-    M = p->M;
-    D = p->D;
-  }else{
-    Y = 2000;  /* If no YMD specified, assume 2000-Jan-01 */
-    M = 1;
-    D = 1;
-  }
-  if( M<=2 ){
-    Y--;
-    M += 12;
-  }
-  A = Y/100;
-  B = 2 - A + (A/4);
-  X1 = 365.25*(Y+4716);
-  X2 = 30.6001*(M+1);
-  p->rJD = X1 + X2 + D + B - 1524.5;
-  p->validJD = 1;
-  if( p->validHMS ){
-    p->rJD += (p->h*3600.0 + p->m*60.0 + p->s)/86400.0;
-    if( p->validTZ ){
-      p->rJD -= p->tz*60/86400.0;
-      p->validYMD = 0;
-      p->validHMS = 0;
-      p->validTZ = 0;
-    }
-  }
-}
-
-/*
-** Parse dates of the form
-**
-**     YYYY-MM-DD HH:MM:SS.FFF
-**     YYYY-MM-DD HH:MM:SS
-**     YYYY-MM-DD HH:MM
-**     YYYY-MM-DD
-**
-** Write the result into the DateTime structure and return 0
-** on success and 1 if the input string is not a well-formed
-** date.
-*/
-static int parseYyyyMmDd(const char *zDate, DateTime *p){
-  int Y, M, D, neg;
-
-  if( zDate[0]=='-' ){
-    zDate++;
-    neg = 1;
-  }else{
-    neg = 0;
-  }
-  if( getDigits(zDate,4,0,9999,'-',&Y,2,1,12,'-',&M,2,1,31,0,&D)!=3 ){
-    return 1;
-  }
-  zDate += 10;
-  while( isspace(*(u8*)zDate) || 'T'==*(u8*)zDate ){ zDate++; }
-  if( parseHhMmSs(zDate, p)==0 ){
-    /* We got the time */
-  }else if( *zDate==0 ){
-    p->validHMS = 0;
-  }else{
-    return 1;
-  }
-  p->validJD = 0;
-  p->validYMD = 1;
-  p->Y = neg ? -Y : Y;
-  p->M = M;
-  p->D = D;
-  if( p->validTZ ){
-    computeJD(p);
-  }
-  return 0;
-}
-
-/*
-** Attempt to parse the given string into a Julian Day Number.  Return
-** the number of errors.
-**
-** The following are acceptable forms for the input string:
-**
-**      YYYY-MM-DD HH:MM:SS.FFF  +/-HH:MM
-**      DDDD.DD 
-**      now
-**
-** In the first form, the +/-HH:MM is always optional.  The fractional
-** seconds extension (the ".FFF") is optional.  The seconds portion
-** (":SS.FFF") is option.  The year and date can be omitted as long
-** as there is a time string.  The time string can be omitted as long
-** as there is a year and date.
-*/
-static int parseDateOrTime(
-  sqlite3_context *context, 
-  const char *zDate, 
-  DateTime *p
-){
-  memset(p, 0, sizeof(*p));
-  if( parseYyyyMmDd(zDate,p)==0 ){
-    return 0;
-  }else if( parseHhMmSs(zDate, p)==0 ){
-    return 0;
-  }else if( sqlite3StrICmp(zDate,"now")==0){
-    double r;
-    sqlite3OsCurrentTime((sqlite3_vfs *)sqlite3_user_data(context), &r);
-    p->rJD = r;
-    p->validJD = 1;
-    return 0;
-  }else if( sqlite3IsNumber(zDate, 0, SQLITE_UTF8) ){
-    getValue(zDate, &p->rJD);
-    p->validJD = 1;
-    return 0;
-  }
-  return 1;
-}
-
-/*
-** Compute the Year, Month, and Day from the julian day number.
-*/
-static void computeYMD(DateTime *p){
-  int Z, A, B, C, D, E, X1;
-  if( p->validYMD ) return;
-  if( !p->validJD ){
-    p->Y = 2000;
-    p->M = 1;
-    p->D = 1;
-  }else{
-    Z = p->rJD + 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;
-    p->D = B - D - X1;
-    p->M = E<14 ? E-1 : E-13;
-    p->Y = p->M>2 ? C - 4716 : C - 4715;
-  }
-  p->validYMD = 1;
-}
-
-/*
-** Compute the Hour, Minute, and Seconds from the julian day number.
-*/
-static void computeHMS(DateTime *p){
-  int Z, s;
-  if( p->validHMS ) return;
-  computeJD(p);
-  Z = p->rJD + 0.5;
-  s = (p->rJD + 0.5 - Z)*86400000.0 + 0.5;
-  p->s = 0.001*s;
-  s = p->s;
-  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 both YMD and HMS
-*/
-static void computeYMD_HMS(DateTime *p){
-  computeYMD(p);
-  computeHMS(p);
-}
-
-/*
-** Clear the YMD and HMS and the TZ
-*/
-static void clearYMD_HMS_TZ(DateTime *p){
-  p->validYMD = 0;
-  p->validHMS = 0;
-  p->validTZ = 0;
-}
-
-/*
-** 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;
-  x = *p;
-  computeYMD_HMS(&x);
-  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;
-#ifdef HAVE_LOCALTIME_R
-  {
-    struct tm sLocal;
-    localtime_r(&t, &sLocal);
-    y.Y = sLocal.tm_year + 1900;
-    y.M = sLocal.tm_mon + 1;
-    y.D = sLocal.tm_mday;
-    y.h = sLocal.tm_hour;
-    y.m = sLocal.tm_min;
-    y.s = sLocal.tm_sec;
-  }
-#else
-  {
-    struct tm *pTm;
-    sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
-    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;
-    sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
-  }
-#endif
-  y.validYMD = 1;
-  y.validHMS = 1;
-  y.validJD = 0;
-  y.validTZ = 0;
-  computeJD(&y);
-  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, zBuf[30];
-  z = zBuf;
-  for(n=0; n<sizeof(zBuf)-1 && zMod[n]; 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);
-        clearYMD_HMS_TZ(p);
-        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;
-        clearYMD_HMS_TZ(p);
-        rc = 0;
-      }else if( strcmp(z, "utc")==0 ){
-        double c1;
-        computeJD(p);
-        c1 = localtimeOffset(p);
-        p->rJD -= c1;
-        clearYMD_HMS_TZ(p);
-        p->rJD += c1 - localtimeOffset(p);
-        rc = 0;
-      }
-      break;
-    }
-    case 'w': {
-      /*
-      **    weekday N
-      **
-      ** Move the date to the same time on the next occurrence of
-      ** weekday N where 0==Sunday, 1==Monday, and so forth.  If the
-      ** date is already on the appropriate weekday, this is a no-op.
-      */
-      if( strncmp(z, "weekday ", 8)==0 && getValue(&z[8],&r)>0
-                 && (n=r)==r && n>=0 && r<7 ){
-        int Z;
-        computeYMD_HMS(p);
-        p->validTZ = 0;
-        p->validJD = 0;
-        computeJD(p);
-        Z = p->rJD + 1.5;
-        Z %= 7;
-        if( Z>n ) Z -= 7;
-        p->rJD += n - Z;
-        clearYMD_HMS_TZ(p);
-        rc = 0;
-      }
-      break;
-    }
-    case 's': {
-      /*
-      **    start of TTTTT
-      **
-      ** Move the date backwards to the beginning of the current day,
-      ** or month or year.
-      */
-      if( strncmp(z, "start of ", 9)!=0 ) break;
-      z += 9;
-      computeYMD(p);
-      p->validHMS = 1;
-      p->h = p->m = 0;
-      p->s = 0.0;
-      p->validTZ = 0;
-      p->validJD = 0;
-      if( strcmp(z,"month")==0 ){
-        p->D = 1;
-        rc = 0;
-      }else if( strcmp(z,"year")==0 ){
-        computeYMD(p);
-        p->M = 1;
-        p->D = 1;
-        rc = 0;
-      }else if( strcmp(z,"day")==0 ){
-        rc = 0;
-      }
-      break;
-    }
-    case '+':
-    case '-':
-    case '0':
-    case '1':
-    case '2':
-    case '3':
-    case '4':
-    case '5':
-    case '6':
-    case '7':
-    case '8':
-    case '9': {
-      n = getValue(z, &r);
-      assert( n>=1 );
-      if( z[n]==':' ){
-        /* A modifier of the form (+|-)HH:MM:SS.FFF adds (or subtracts) the
-        ** specified number of hours, minutes, seconds, and fractional seconds
-        ** to the time.  The ".FFF" may be omitted.  The ":SS.FFF" may be
-        ** omitted.
-        */
-        const char *z2 = z;
-        DateTime tx;
-        int day;
-        if( !isdigit(*(u8*)z2) ) z2++;
-        memset(&tx, 0, sizeof(tx));
-        if( parseHhMmSs(z2, &tx) ) break;
-        computeJD(&tx);
-        tx.rJD -= 0.5;
-        day = (int)tx.rJD;
-        tx.rJD -= day;
-        if( z[0]=='-' ) tx.rJD = -tx.rJD;
-        computeJD(p);
-        clearYMD_HMS_TZ(p);
-        p->rJD += tx.rJD;
-        rc = 0;
-        break;
-      }
-      z += n;
-      while( isspace(*(u8*)z) ) z++;
-      n = strlen(z);
-      if( n>10 || n<3 ) break;
-      if( z[n-1]=='s' ){ z[n-1] = 0; n--; }
-      computeJD(p);
-      rc = 0;
-      if( n==3 && strcmp(z,"day")==0 ){
-        p->rJD += r;
-      }else if( n==4 && strcmp(z,"hour")==0 ){
-        p->rJD += r/24.0;
-      }else if( n==6 && strcmp(z,"minute")==0 ){
-        p->rJD += r/(24.0*60.0);
-      }else if( n==6 && strcmp(z,"second")==0 ){
-        p->rJD += r/(24.0*60.0*60.0);
-      }else if( n==5 && strcmp(z,"month")==0 ){
-        int x, y;
-        computeYMD_HMS(p);
-        p->M += r;
-        x = p->M>0 ? (p->M-1)/12 : (p->M-12)/12;
-        p->Y += x;
-        p->M -= x*12;
-        p->validJD = 0;
-        computeJD(p);
-        y = r;
-        if( y!=r ){
-          p->rJD += (r - y)*30.0;
-        }
-      }else if( n==4 && strcmp(z,"year")==0 ){
-        computeYMD_HMS(p);
-        p->Y += r;
-        p->validJD = 0;
-        computeJD(p);
-      }else{
-        rc = 1;
-      }
-      clearYMD_HMS_TZ(p);
-      break;
-    }
-    default: {
-      break;
-    }
-  }
-  return rc;
-}
-
-/*
-** Process time function arguments.  argv[0] is a date-time stamp.
-** argv[1] and following are modifiers.  Parse them all and write
-** the resulting time into the DateTime structure p.  Return 0
-** on success and 1 if there are any errors.
-*/
-static int isDate(
-  sqlite3_context *context, 
-  int argc, 
-  sqlite3_value **argv, 
-  DateTime *p
-){
-  int i;
-  const unsigned char *z;
-  if( argc==0 ) return 1;
-  z = sqlite3_value_text(argv[0]);
-  if( !z || parseDateOrTime(context, (char*)z, p) ){
-    return 1;
-  }
-  for(i=1; i<argc; i++){
-    if( (z = sqlite3_value_text(argv[i]))==0 || parseModifier((char*)z, p) ){
-      return 1;
-    }
-  }
-  return 0;
-}
-
-
-/*
-** The following routines implement the various date and time functions
-** of SQLite.
-*/
-
-/*
-**    julianday( TIMESTRING, MOD, MOD, ...)
-**
-** Return the julian day number of the date specified in the arguments
-*/
-static void juliandayFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  DateTime x;
-  if( isDate(context, argc, argv, &x)==0 ){
-    computeJD(&x);
-    sqlite3_result_double(context, x.rJD);
-  }
-}
-
-/*
-**    datetime( TIMESTRING, MOD, MOD, ...)
-**
-** Return YYYY-MM-DD HH:MM:SS
-*/
-static void datetimeFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  DateTime x;
-  if( isDate(context, argc, argv, &x)==0 ){
-    char zBuf[100];
-    computeYMD_HMS(&x);
-    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d %02d:%02d:%02d",
-                     x.Y, x.M, x.D, x.h, x.m, (int)(x.s));
-    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
-  }
-}
-
-/*
-**    time( TIMESTRING, MOD, MOD, ...)
-**
-** Return HH:MM:SS
-*/
-static void timeFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  DateTime x;
-  if( isDate(context, argc, argv, &x)==0 ){
-    char zBuf[100];
-    computeHMS(&x);
-    sqlite3_snprintf(sizeof(zBuf), zBuf, "%02d:%02d:%02d", x.h, x.m, (int)x.s);
-    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
-  }
-}
-
-/*
-**    date( TIMESTRING, MOD, MOD, ...)
-**
-** Return YYYY-MM-DD
-*/
-static void dateFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  DateTime x;
-  if( isDate(context, argc, argv, &x)==0 ){
-    char zBuf[100];
-    computeYMD(&x);
-    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d", x.Y, x.M, x.D);
-    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
-  }
-}
-
-/*
-**    strftime( FORMAT, TIMESTRING, MOD, MOD, ...)
-**
-** Return a string described by FORMAT.  Conversions as follows:
-**
-**   %d  day of month
-**   %f  ** fractional seconds  SS.SSS
-**   %H  hour 00-24
-**   %j  day of year 000-366
-**   %J  ** Julian day number
-**   %m  month 01-12
-**   %M  minute 00-59
-**   %s  seconds since 1970-01-01
-**   %S  seconds 00-59
-**   %w  day of week 0-6  sunday==0
-**   %W  week of year 00-53
-**   %Y  year 0000-9999
-**   %%  %
-*/
-static void strftimeFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  DateTime x;
-  u64 n;
-  int i, j;
-  char *z;
-  const char *zFmt = (const char*)sqlite3_value_text(argv[0]);
-  char zBuf[100];
-  if( zFmt==0 || isDate(context, argc-1, argv+1, &x) ) return;
-  for(i=0, n=1; zFmt[i]; i++, n++){
-    if( zFmt[i]=='%' ){
-      switch( zFmt[i+1] ){
-        case 'd':
-        case 'H':
-        case 'm':
-        case 'M':
-        case 'S':
-        case 'W':
-          n++;
-          /* fall thru */
-        case 'w':
-        case '%':
-          break;
-        case 'f':
-          n += 8;
-          break;
-        case 'j':
-          n += 3;
-          break;
-        case 'Y':
-          n += 8;
-          break;
-        case 's':
-        case 'J':
-          n += 50;
-          break;
-        default:
-          return;  /* ERROR.  return a NULL */
-      }
-      i++;
-    }
-  }
-  if( n<sizeof(zBuf) ){
-    z = zBuf;
-  }else if( n>SQLITE_MAX_LENGTH ){
-    sqlite3_result_error_toobig(context);
-    return;
-  }else{
-    z = (char*)sqlite3_malloc( n );
-    if( z==0 ) return;
-  }
-  computeJD(&x);
-  computeYMD_HMS(&x);
-  for(i=j=0; zFmt[i]; i++){
-    if( zFmt[i]!='%' ){
-      z[j++] = zFmt[i];
-    }else{
-      i++;
-      switch( zFmt[i] ){
-        case 'd':  sqlite3_snprintf(3, &z[j],"%02d",x.D); j+=2; break;
-        case 'f': {
-          double s = x.s;
-          if( s>59.999 ) s = 59.999;
-          sqlite3_snprintf(7, &z[j],"%06.3f", s);
-          j += strlen(&z[j]);
-          break;
-        }
-        case 'H':  sqlite3_snprintf(3, &z[j],"%02d",x.h); j+=2; break;
-        case 'W': /* Fall thru */
-        case 'j': {
-          int nDay;             /* Number of days since 1st day of year */
-          DateTime y = x;
-          y.validJD = 0;
-          y.M = 1;
-          y.D = 1;
-          computeJD(&y);
-          nDay = x.rJD - y.rJD + 0.5;
-          if( zFmt[i]=='W' ){
-            int wd;   /* 0=Monday, 1=Tuesday, ... 6=Sunday */
-            wd = ((int)(x.rJD+0.5)) % 7;
-            sqlite3_snprintf(3, &z[j],"%02d",(nDay+7-wd)/7);
-            j += 2;
-          }else{
-            sqlite3_snprintf(4, &z[j],"%03d",nDay+1);
-            j += 3;
-          }
-          break;
-        }
-        case 'J': {
-          sqlite3_snprintf(20, &z[j],"%.16g",x.rJD);
-          j+=strlen(&z[j]);
-          break;
-        }
-        case 'm':  sqlite3_snprintf(3, &z[j],"%02d",x.M); j+=2; break;
-        case 'M':  sqlite3_snprintf(3, &z[j],"%02d",x.m); j+=2; break;
-        case 's': {
-          sqlite3_snprintf(30,&z[j],"%d",
-                           (int)((x.rJD-2440587.5)*86400.0 + 0.5));
-          j += strlen(&z[j]);
-          break;
-        }
-        case 'S':  sqlite3_snprintf(3,&z[j],"%02d",(int)x.s); j+=2; break;
-        case 'w':  z[j++] = (((int)(x.rJD+1.5)) % 7) + '0'; break;
-        case 'Y':  sqlite3_snprintf(5,&z[j],"%04d",x.Y); j+=strlen(&z[j]);break;
-        case '%':  z[j++] = '%'; break;
-      }
-    }
-  }
-  z[j] = 0;
-  sqlite3_result_text(context, z, -1, SQLITE_TRANSIENT);
-  if( z!=zBuf ){
-    sqlite3_free(z);
-  }
-}
-
-/*
-** current_time()
-**
-** This function returns the same value as time('now').
-*/
-static void ctimeFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  sqlite3_value *pVal = sqlite3ValueNew(0);
-  if( pVal ){
-    sqlite3ValueSetStr(pVal, -1, "now", SQLITE_UTF8, SQLITE_STATIC);
-    timeFunc(context, 1, &pVal);
-    sqlite3ValueFree(pVal);
-  }
-}
-
-/*
-** current_date()
-**
-** This function returns the same value as date('now').
-*/
-static void cdateFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  sqlite3_value *pVal = sqlite3ValueNew(0);
-  if( pVal ){
-    sqlite3ValueSetStr(pVal, -1, "now", SQLITE_UTF8, SQLITE_STATIC);
-    dateFunc(context, 1, &pVal);
-    sqlite3ValueFree(pVal);
-  }
-}
-
-/*
-** current_timestamp()
-**
-** This function returns the same value as datetime('now').
-*/
-static void ctimestampFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  sqlite3_value *pVal = sqlite3ValueNew(0);
-  if( pVal ){
-    sqlite3ValueSetStr(pVal, -1, "now", SQLITE_UTF8, SQLITE_STATIC);
-    datetimeFunc(context, 1, &pVal);
-    sqlite3ValueFree(pVal);
-  }
-}
-#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */
-
-#ifdef SQLITE_OMIT_DATETIME_FUNCS
-/*
-** If the library is compiled to omit the full-scale date and time
-** handling (to get a smaller binary), the following minimal version
-** of the functions current_time(), current_date() and current_timestamp()
-** are included instead. This is to support column declarations that
-** include "DEFAULT CURRENT_TIME" etc.
-**
-** This function uses the C-library functions time(), gmtime()
-** and strftime(). The format string to pass to strftime() is supplied
-** as the user-data for the function.
-*/
-static void currentTimeFunc(
-  sqlite3_context *context,
-  int argc,
-  sqlite3_value **argv
-){
-  time_t t;
-  char *zFormat = (char *)sqlite3_user_data(context);
-  char zBuf[20];
-
-  time(&t);
-#ifdef SQLITE_TEST
-  {
-    extern int sqlite3_current_time;  /* See os_XXX.c */
-    if( sqlite3_current_time ){
-      t = sqlite3_current_time;
-    }
-  }
-#endif
-
-#ifdef HAVE_GMTIME_R
-  {
-    struct tm sNow;
-    gmtime_r(&t, &sNow);
-    strftime(zBuf, 20, zFormat, &sNow);
-  }
-#else
-  {
-    struct tm *pTm;
-    sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
-    pTm = gmtime(&t);
-    strftime(zBuf, 20, zFormat, pTm);
-    sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
-  }
-#endif
-
-  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
-}
-#endif
-
-/*
-** This function registered all of the above C functions as SQL
-** functions.  This should be the only routine in this file with
-** external linkage.
-*/
-void sqlite3RegisterDateTimeFunctions(sqlite3 *db){
-#ifndef SQLITE_OMIT_DATETIME_FUNCS
-  static const struct {
-     char *zName;
-     int nArg;
-     void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
-  } aFuncs[] = {
-    { "julianday", -1, juliandayFunc   },
-    { "date",      -1, dateFunc        },
-    { "time",      -1, timeFunc        },
-    { "datetime",  -1, datetimeFunc    },
-    { "strftime",  -1, strftimeFunc    },
-    { "current_time",       0, ctimeFunc      },
-    { "current_timestamp",  0, ctimestampFunc },
-    { "current_date",       0, cdateFunc      },
-  };
-  int i;
-
-  for(i=0; i<sizeof(aFuncs)/sizeof(aFuncs[0]); i++){
-    sqlite3CreateFunc(db, aFuncs[i].zName, aFuncs[i].nArg,
-        SQLITE_UTF8, (void *)(db->pVfs), aFuncs[i].xFunc, 0, 0);
-  }
-#else
-  static const struct {
-     char *zName;
-     char *zFormat;
-  } aFuncs[] = {
-    { "current_time", "%H:%M:%S" },
-    { "current_date", "%Y-%m-%d" },
-    { "current_timestamp", "%Y-%m-%d %H:%M:%S" }
-  };
-  int i;
-
-  for(i=0; i<sizeof(aFuncs)/sizeof(aFuncs[0]); i++){
-    sqlite3CreateFunc(db, aFuncs[i].zName, 0, SQLITE_UTF8, 
-        aFuncs[i].zFormat, currentTimeFunc, 0, 0);
-  }
-#endif
-}