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 1.27 2003/08/09 21:32:28 drh Exp $
*/
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#include "sqliteInt.h"
#include "os.h"

/*
** Implementation of the non-aggregate min() and max() functions
*/
static void minFunc(sqlite_func *context, int argc, const char **argv){
  const char *zBest; 
  int i;

    sqlite_set_result_string(context, p->z, strlen(p->z));
  }
  if( p && p->z && p->z!=p->zBuf ){
    sqliteFree(p->z);
  }
}

/****************************************************************************
** Time and date functions.
**
** 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)
** 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
** 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)
*/
#ifndef SQLITE_OMIT_DATETIME_FUNCS

/*
** Convert N digits from zDate into an integer.  Return
** -1 if zDate does not begin with N digits.
*/
static int getDigits(const char *zDate, int N){
  int val = 0;
  while( N-- ){
    if( !isdigit(*zDate) ) return -1;
    val = val*10 + *zDate - '0';
    zDate++;
  }
  return val;
}

/*
** Parse dates 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.
*/
static int parseHhMmSs(const char *zDate, double *prJD){
  int h, m, s;
  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;
  }else{
    s = 0;
  }
  while( isspace(*zDate) ){ zDate++; }
  *prJD = (h*3600.0 + m*60.0 + s)/86400.0;
  return 0;
}

/*
** Parse dates of the form
**
**     YYYY-MM-DD HH:MM:SS
**     YYYY-MM-DD HH:MM
**     YYYY-MM-DD
**
** Write the result as a julian day number in *prJD.  Return 0
** on success and 1 if the input string is not a well-formed
** date.
*/
static int parseYyyyMmDd(const char *zDate, double *prJD){
  int Y, M, D;
  double rTime;
  int A, B, X1, X2;

  Y = getDigits(zDate, 4);
  if( Y<0 || zDate[4]!='-' ) return 1;
  zDate += 5;
  M = getDigits(zDate, 2);
  if( M<=0 || M>12 || zDate[2]!='-' ) return 1;
  zDate += 3;
  D = getDigits(zDate, 2);
  if( D<=0 || D>31 ) return 1;
  zDate += 2;
  while( isspace(*zDate) ){ zDate++; }
  if( isdigit(*zDate) ){
    if( parseHhMmSs(zDate, &rTime) ) return 1;
  }else if( *zDate==0 ){
    rTime = 0.0;
  }else{ 
    return 1;
  }

  /* The year, month, and day are now stored in Y, M, and D.  Convert
  ** these into the Julian Day number.  See Meeus page 61.
  */
  if( M<=2 ){
    Y--;
    M += 12;
  }
  A = Y/100;
  B = 2 - A + (A/4);
  X1 = 365.25*(Y+4716);
  X2 = 30.6001*(M+1);
  *prJD = X1 + X2 + D + B - 1524.5 + rTime;
  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
**      YYYY-MM-DD HH:MM
**      YYYY-MM-DD HH:MM:SS
**      HH:MM
**      HH:MM:SS
**      DDDD.DD 
**      now
*/
static int parseDateOrTime(const char *zDate, 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]==':' ){
    return parseHhMmSs(zDate, prJD);
  }else if( i==0 && sqliteStrICmp(zDate,"now")==0 ){
    return sqliteOsCurrentTime(prJD);
  }else if( sqliteIsNumber(zDate) ){
    *prJD = atof(zDate);
    return 0;
  }
  return 1;
}

/*
** Break up a julian day number into year, month, day, and seconds.
** This function assume the Gregorian calendar - even for dates prior
** to the invention of the Gregorian calendar in 1582.
**
** See Meeus page 63.
*/
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
){
  double r;
  int i;
  *prJD = 0.0;
  for(i=0; i<argc; i++){
    if( argv[i]==0 ) return 0;
    if( parseDateOrTime(argv[i], &r) ) return 0;
    *prJD += r;
  }
  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);
  }
}
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;
    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);
    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;
    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);
    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;
    char zBuf[100];
    decomposeDate(JD, &Y, &M, &D, &s);
    sprintf(zBuf, "%04d-%02d-%02d", Y, M, 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);
  }
}
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);
  }
}
static void dayofweekFunc(sqlite_func *context, int argc, const char **argv){
  double JD;
  if( isDate(context, argc, argv, &JD) ){
    int Z = JD + 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);
  }
}
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);
  }
}
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);
  }
}
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);
  }
}
#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.
*/
void sqliteRegisterBuiltinFunctions(sqlite *db){
  static struct {

    { "coalesce",   1, 0,              0          },
    { "ifnull",     2, SQLITE_ARGS,    ifnullFunc },
    { "random",    -1, SQLITE_NUMERIC, randomFunc },
    { "like",       2, SQLITE_NUMERIC, likeFunc   },
    { "glob",       2, SQLITE_NUMERIC, globFunc   },
    { "nullif",     2, SQLITE_ARGS,    nullifFunc },
    { "sqlite_version",0,SQLITE_TEXT,  versionFunc},
#ifndef SQLITE_OMIT_DATETIME_FUNCS
    { "julianday", -1, SQLITE_NUMERIC, juliandayFunc   },
    { "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   },
    { "hour",      -1, SQLITE_NUMERIC, hourFunc        },
    { "minute",    -1, SQLITE_NUMERIC, minuteFunc      },
    { "second",    -1, SQLITE_NUMERIC, secondFunc      },
#endif
#ifdef SQLITE_SOUNDEX
    { "soundex",    1, SQLITE_TEXT,    soundexFunc},
#endif
#ifdef SQLITE_TEST
    { "randstr",    2, SQLITE_TEXT,    randStr    },
#endif
  };

    char zBuf[_MAX_PATH+1];
      sqliteSetString(&zFull, getcwd(zBuf, sizeof(zBuf)), zRelative, 0);
    }
  }
  return zFull;
#endif
}

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
int sqliteOsCurrentTime(double *prNow){
#if OS_UNIX
  time_t t;
  time(&t);
  *prNow = t/86400.0 + 2440587.5;
  return 0;
#endif
  return 1;
}

int sqliteOsTruncate(OsFile*, off_t size);
int sqliteOsFileSize(OsFile*, off_t *pSize);
int sqliteOsReadLock(OsFile*);
int sqliteOsWriteLock(OsFile*);
int sqliteOsUnlock(OsFile*);
int sqliteOsRandomSeed(char*);
int sqliteOsSleep(int ms);
int sqliteOsCurrentTime(double*);
void sqliteOsEnterMutex(void);
void sqliteOsLeaveMutex(void);
char *sqliteOsFullPathname(const char*);



#endif /* _SQLITE_OS_H_ */

/*
** 2001 September 15
**
** 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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.196 2003/08/09 21:32:28 drh Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"

** you can define one or more of the following macros to omit extra
** features of the library and thus keep the size of the library to
** a minimum.
*/
/* #define SQLITE_OMIT_AUTHORIZATION  1 */
/* #define SQLITE_OMIT_INMEMORYDB     1 */
/* #define SQLITE_OMIT_VACUUM         1 */
/* #define SQLITE_OMIT_TIMEDATE_FUNCS 1 */

/*
** Integers of known sizes.  These typedefs might change for architectures
** where the sizes very.  Preprocessor macros are available so that the
** types can be conveniently redefined at compile-type.  Like this:
**
**         cc '-DUINTPTR_TYPE=long long int' ...