SQLite

** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.32 2003/10/10 02:09:57 drh Exp $
*/
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#include "sqliteInt.h"
#include "os.h"

    val = val*10 + *zDate - '0';
    zDate++;
  }
  return val;
}

/*
** Parse a timezone extension on the end of a datetime stamp.
** 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, int *pnMin){
  int sgn = 0;
  int nHr, nMn;
  while( isspace(*zDate) ){ zDate++; }
  *pnMin = 0;
  if( *zDate=='-' ){
    sgn = -1;
  }else if( *zDate=='+' ){
    sgn = +1;
  }else{
    return *zDate!=0;
  }
  zDate++;
  nHr = getDigits(zDate, 2);
  if( nHr<0 || nHr>14 ) return 1;
  zDate += 2;
  if( zDate[0]!=':' ) return 1;
  zDate++;
  nMn = getDigits(zDate, 2);
  if( nMn<0 || nMn>59 ) return 1;
  zDate += 2;
  *pnMin = sgn*(nMn + nHr*60);
  while( isspace(*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.
**
** The time string can be followed by an optional timezone specifier
** of the following form:  (+/-)HH:MM.
**
** Whatever the format, the string is converted into a julian
** day number and stored in *prJD.
**
** Return 1 if there is a parsing error and 0 on success.
*/
static int parseHhMmSs(const char *zDate, double *prJD){
  int h, m, s, tz;
  double ms = 0.0;
  h = getDigits(zDate, 2);
  if( h<0 || zDate[2]!=':' ) return 1;
  zDate += 3;
  m = getDigits(zDate, 2);
  if( m<0 || m>59 ) return 1;
  zDate += 2;
  if( *zDate==':' ){
    s = getDigits(&zDate[1], 2);
    if( s<0 || s>59 ) return 1;
    zDate += 3;
    if( *zDate=='.' && isdigit(zDate[1]) ){
      double rScale = 1.0/864000.0;
      zDate++;
      while( isdigit(*zDate) ){
        ms += rScale * (*zDate - '0');
        rScale *= 0.1;
        zDate++;
      }
    }
  }else{
    s = 0;
  }
  if( parseTimezone(zDate, &tz) ) return 1;
  *prJD = (h*3600.0 + (m+tz)*60.0 + s)/86400.0 + ms;
  return 0;
}

/*
** Parse dates of the form
**
**     YYYY-MM-DD HH:MM:SS

/*
** 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.
**
** If the bRelative flag is set and the format is HH:MM or HH:MM:SS then
** make the result is relative to midnight instead of noon.  In other words,
** if bRelative is true, "00:00:00" parses to 0.0 but if bRelative is
** false, "00:00:00" parses to 0.5.
*/
static int parseDateOrTime(const char *zDate, int bRelative, double *prJD){
  int i;
  for(i=0; isdigit(zDate[i]); i++){}
  if( i==4 && zDate[i]=='-' ){
    return parseYyyyMmDd(zDate, prJD);
  }else if( i==2 && zDate[i]==':' ){
    if( parseHhMmSs(zDate, prJD) ) return 1;
    if( !bRelative ) *prJD += 2451544.5;
    return 0;
  }else if( i==0 && sqliteStrICmp(zDate,"now")==0 ){
    return sqliteOsCurrentTime(prJD);
  }else if( sqliteIsNumber(zDate) ){
    *prJD = atof(zDate);
    return 0;
  }
  return 1;
}

/*
** 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;      /* Hour and minutes */
  double s;      /* Seconds */
};

/*
** 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.
**

    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 ){
    int 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;
  }
}

/*
** 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

*/
static int isDate(int argc, const char **argv, DateTime *p, int mode){
  double r;
  int i;
  p->rJD = 0.0;
  for(i=0; i<argc; i++){
    if( argv[i]==0 ) return 0;
    if( parseDateOrTime(argv[i], i, &r) ) return 0;
    p->rJD += r;
  }
  decomposeDate(p, mode);
  return 1;
}

    sqlite_set_result_double(context, x.rJD);
  }
}
static void timestampFunc(sqlite_func *context, int argc, const char **argv){
  DateTime x;
  if( isDate(argc, argv, &x, 3) ){
    char zBuf[100];
    sprintf(zBuf, "%04d-%02d-%02d %02d:%02d:%02d",x.Y, x.M, x.D, x.h, x.m,
           (int)(x.s+0.5));
    sqlite_set_result_string(context, zBuf, -1);
  }
}
static void timeFunc(sqlite_func *context, int argc, const char **argv){
  DateTime x;
  if( isDate(argc, argv, &x, 2) ){
    char zBuf[100];
    sprintf(zBuf, "%02d:%02d:%02d", x.h, x.m, (int)(x.s+0.5));
    sqlite_set_result_string(context, zBuf, -1);
  }
}
static void dateFunc(sqlite_func *context, int argc, const char **argv){
  DateTime x;
  if( isDate(argc, argv, &x, 1) ){
    char zBuf[100];

  if( isDate(argc, argv, &x, 1) ){
    sqlite_set_result_int(context, x.D);
  }
}
static void secondFunc(sqlite_func *context, int argc, const char **argv){
  DateTime x;
  if( isDate(argc, argv, &x, 2) ){
    sqlite_set_result_double(context, x.s);
  }
}
static void minuteFunc(sqlite_func *context, int argc, const char **argv){
  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){
  DateTime x;
  if( isDate(argc, argv, &x, 2) ){
    sqlite_set_result_int(context, x.h);
  }
}
static void unixToJdFunc(sqlite_func *context, int argc, const char **argv){
  sqlite_set_result_double(context, atof(argv[0])/(24.0*3600.0)+2440587.5);
}
static void unixtimeFunc(sqlite_func *context, int argc, const char **argv){
  DateTime x;
  if( isDate(argc, argv, &x, 0) ){
    sqlite_set_result_double(context, (x.rJD-2440587.5)*24.0*3600.0);
  }
}

#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */
/***************************************************************************/

/*
** This function registered all of the above C functions as SQL
** functions.  This should be the only routine in this file with
** external linkage.

    { "like",       2, SQLITE_NUMERIC, likeFunc   },
    { "glob",       2, SQLITE_NUMERIC, globFunc   },
    { "nullif",     2, SQLITE_ARGS,    nullifFunc },
    { "sqlite_version",0,SQLITE_TEXT,  versionFunc},
    { "quote",      1, SQLITE_ARGS,    quoteFunc  },
#ifndef SQLITE_OMIT_DATETIME_FUNCS
    { "julianday", -1, SQLITE_NUMERIC, juliandayFunc   },
    { "unixtime",  -1, SQLITE_NUMERIC, unixtimeFunc    },
    { "unix_to_jd", 1, SQLITE_NUMERIC, unixToJdFunc    },
    { "timestamp", -1, SQLITE_TEXT,    timestampFunc   },
    { "time",      -1, SQLITE_TEXT,    timeFunc        },
    { "date",      -1, SQLITE_TEXT,    dateFunc        },
    { "year",      -1, SQLITE_NUMERIC, yearFunc        },
    { "month",     -1, SQLITE_NUMERIC, monthFunc       },
    { "dayofmonth",-1, SQLITE_NUMERIC, dayofmonthFunc  },
    { "dayofweek", -1, SQLITE_NUMERIC, dayofweekFunc   },

  sqlite_set_result_string(p, zMsg, n);
  p->isError = 1;
}

/*
** Extract the user data from a sqlite_func structure and return a
** pointer to it.




*/
void *sqlite_user_data(sqlite_func *p){
  assert( p && p->pFunc );
  return p->pFunc->pUserData;
}

/*