/*

** 2002 February 23

**

** 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 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 1.203 2008/09/03 17:11:16 drh Exp $

*/

#include "sqliteInt.h"

#include <ctype.h>

#include <stdlib.h>

#include <assert.h>

#include "vdbeInt.h"

/*

** Return the collating function associated with a function.

*/

static CollSeq *sqlite3GetFuncCollSeq(sqlite3_context *context){

  return context->pColl;

}

/*

** Implementation of the non-aggregate min() and max() functions

*/

static void minmaxFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  int i;

  int mask;    /* 0 for min() or 0xffffffff for max() */

  int iBest;

  CollSeq *pColl;

  if( argc==0 ) return;

  mask = sqlite3_user_data(context)==0 ? 0 : -1;

  pColl = sqlite3GetFuncCollSeq(context);

  assert( pColl );

  assert( mask==-1 || mask==0 );

  iBest = 0;

  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;

  for(i=1; i<argc; i++){

    if( sqlite3_value_type(argv[i])==SQLITE_NULL ) return;

    if( (sqlite3MemCompare(argv[iBest], argv[i], pColl)^mask)>=0 ){

      iBest = i;

    }

  }

  sqlite3_result_value(context, argv[iBest]);

}

/*

** Return the type of the argument.

*/

static void typeofFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  const char *z = 0;

  switch( sqlite3_value_type(argv[0]) ){

    case SQLITE_NULL:    z = "null";    break;

    case SQLITE_INTEGER: z = "integer"; break;

    case SQLITE_TEXT:    z = "text";    break;

    case SQLITE_FLOAT:   z = "real";    break;

    case SQLITE_BLOB:    z = "blob";    break;

  }

  sqlite3_result_text(context, z, -1, SQLITE_STATIC);

}

/*

** Implementation of the length() function

*/

static void lengthFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  int len;

  assert( argc==1 );

  switch( sqlite3_value_type(argv[0]) ){

    case SQLITE_BLOB:

    case SQLITE_INTEGER:

    case SQLITE_FLOAT: {

      sqlite3_result_int(context, sqlite3_value_bytes(argv[0]));

      break;

    }

    case SQLITE_TEXT: {

      const unsigned char *z = sqlite3_value_text(argv[0]);

      if( z==0 ) return;

      len = 0;

      while( *z ){

        len++;

        SQLITE_SKIP_UTF8(z);

      }

      sqlite3_result_int(context, len);

      break;

    }

    default: {

      sqlite3_result_null(context);

      break;

    }

  }

}

/*

** Implementation of the abs() function

*/

static void absFunc(sqlite3_context *context, int argc, sqlite3_value **argv){

  assert( argc==1 );

  switch( sqlite3_value_type(argv[0]) ){

    case SQLITE_INTEGER: {

      i64 iVal = sqlite3_value_int64(argv[0]);

      if( iVal<0 ){

        if( (iVal<<1)==0 ){

          sqlite3_result_error(context, "integer overflow", -1);

          return;

        }

        iVal = -iVal;

      } 

      sqlite3_result_int64(context, iVal);

      break;

    }

    case SQLITE_NULL: {

      sqlite3_result_null(context);

      break;

    }

    default: {

      double rVal = sqlite3_value_double(argv[0]);

      if( rVal<0 ) rVal = -rVal;

      sqlite3_result_double(context, rVal);

      break;

    }

  }

}

/*

** Implementation of the substr() function.

**

** substr(x,p1,p2)  returns p2 characters of x[] beginning with p1.

** p1 is 1-indexed.  So substr(x,1,1) returns the first character

** of x.  If x is text, then we actually count UTF-8 characters.

** If x is a blob, then we count bytes.

**

** If p1 is negative, then we begin abs(p1) from the end of x[].

*/

static void substrFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  const unsigned char *z;

  const unsigned char *z2;

  int len;

  int p0type;

  i64 p1, p2;

  assert( argc==3 || argc==2 );

  p0type = sqlite3_value_type(argv[0]);

  if( p0type==SQLITE_BLOB ){

    len = sqlite3_value_bytes(argv[0]);

    z = sqlite3_value_blob(argv[0]);

    if( z==0 ) return;

    assert( len==sqlite3_value_bytes(argv[0]) );

  }else{

    z = sqlite3_value_text(argv[0]);

    if( z==0 ) return;

    len = 0;

    for(z2=z; *z2; len++){

      SQLITE_SKIP_UTF8(z2);

    }

  }

  p1 = sqlite3_value_int(argv[1]);

  if( argc==3 ){

    p2 = sqlite3_value_int(argv[2]);

  }else{

    p2 = sqlite3_context_db_handle(context)->aLimit[SQLITE_LIMIT_LENGTH];

  }

  if( p1<0 ){

    p1 += len;

    if( p1<0 ){

      p2 += p1;

      p1 = 0;

    }

  }else if( p1>0 ){

    p1--;

  }

  if( p1+p2>len ){

    p2 = len-p1;

  }

  if( p0type!=SQLITE_BLOB ){

    while( *z && p1 ){

      SQLITE_SKIP_UTF8(z);

      p1--;

    }

    for(z2=z; *z2 && p2; p2--){

      SQLITE_SKIP_UTF8(z2);

    }

    sqlite3_result_text(context, (char*)z, z2-z, SQLITE_TRANSIENT);

  }else{

    if( p2<0 ) p2 = 0;

    sqlite3_result_blob(context, (char*)&z[p1], p2, SQLITE_TRANSIENT);

  }

}

/*

** Implementation of the round() function

*/

static void roundFunc(sqlite3_context *context, int argc, sqlite3_value **argv){

  int n = 0;

  double r;

  char zBuf[500];  /* larger than the %f representation of the largest double */

  assert( argc==1 || argc==2 );

  if( argc==2 ){

    if( SQLITE_NULL==sqlite3_value_type(argv[1]) ) return;

    n = sqlite3_value_int(argv[1]);

    if( n>30 ) n = 30;

    if( n<0 ) n = 0;

  }

  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;

  r = sqlite3_value_double(argv[0]);

  sqlite3_snprintf(sizeof(zBuf),zBuf,"%.*f",n,r);

  sqlite3AtoF(zBuf, &r);

  sqlite3_result_double(context, r);

}

/*

** Allocate nByte bytes of space using sqlite3_malloc(). If the

** allocation fails, call sqlite3_result_error_nomem() to notify

** the database handle that malloc() has failed.

*/

static void *contextMalloc(sqlite3_context *context, i64 nByte){

  char *z;

  if( nByte>sqlite3_context_db_handle(context)->aLimit[SQLITE_LIMIT_LENGTH] ){

    sqlite3_result_error_toobig(context);

    z = 0;

  }else{

    z = sqlite3Malloc(nByte);

    if( !z && nByte>0 ){

      sqlite3_result_error_nomem(context);

    }

  }

  return z;

}

/*

** Implementation of the upper() and lower() SQL functions.

*/

static void upperFunc(sqlite3_context *context, int argc, sqlite3_value **argv){

  char *z1;

  const char *z2;

  int i, n;

  if( argc<1 || SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;

  z2 = (char*)sqlite3_value_text(argv[0]);

  n = sqlite3_value_bytes(argv[0]);

  /* Verify that the call to _bytes() does not invalidate the _text() pointer */

  assert( z2==(char*)sqlite3_value_text(argv[0]) );

  if( z2 ){

    z1 = contextMalloc(context, ((i64)n)+1);

    if( z1 ){

      memcpy(z1, z2, n+1);

      for(i=0; z1[i]; i++){

        z1[i] = toupper(z1[i]);

      }

      sqlite3_result_text(context, z1, -1, sqlite3_free);

    }

  }

}

static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){

  char *z1;

  const char *z2;

  int i, n;

  if( argc<1 || SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;

  z2 = (char*)sqlite3_value_text(argv[0]);

  n = sqlite3_value_bytes(argv[0]);

  /* Verify that the call to _bytes() does not invalidate the _text() pointer */

  assert( z2==(char*)sqlite3_value_text(argv[0]) );

  if( z2 ){

    z1 = contextMalloc(context, ((i64)n)+1);

    if( z1 ){

      memcpy(z1, z2, n+1);

      for(i=0; z1[i]; i++){

        z1[i] = tolower(z1[i]);

      }

      sqlite3_result_text(context, z1, -1, sqlite3_free);

    }

  }

}

/*

** Implementation of the IFNULL(), NVL(), and COALESCE() functions.  

** All three do the same thing.  They return the first non-NULL

** argument.

*/

static void ifnullFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  int i;

  for(i=0; i<argc; i++){

    if( SQLITE_NULL!=sqlite3_value_type(argv[i]) ){

      sqlite3_result_value(context, argv[i]);

      break;

    }

  }

}

/*

** Implementation of random().  Return a random integer.  

*/

static void randomFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  sqlite_int64 r;

  sqlite3_randomness(sizeof(r), &r);

  if( (r<<1)==0 ) r = 0;  /* Prevent 0x8000.... as the result so that we */

                          /* can always do abs() of the result */

  sqlite3_result_int64(context, r);

}

/*

** Implementation of randomblob(N).  Return a random blob

** that is N bytes long.

*/

static void randomBlob(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  int n;

  unsigned char *p;

  assert( argc==1 );

  n = sqlite3_value_int(argv[0]);

  if( n<1 ){

    n = 1;

  }

  p = contextMalloc(context, n);

  if( p ){

    sqlite3_randomness(n, p);

    sqlite3_result_blob(context, (char*)p, n, sqlite3_free);

  }

}

/*

** Implementation of the last_insert_rowid() SQL function.  The return

** value is the same as the sqlite3_last_insert_rowid() API function.

*/

static void last_insert_rowid(

  sqlite3_context *context, 

  int arg, 

  sqlite3_value **argv

){

  sqlite3 *db = sqlite3_context_db_handle(context);

  sqlite3_result_int64(context, sqlite3_last_insert_rowid(db));

}

/*

** Implementation of the changes() SQL function.  The return value is the

** same as the sqlite3_changes() API function.

*/

static void changes(

  sqlite3_context *context,

  int arg,

  sqlite3_value **argv

){

  sqlite3 *db = sqlite3_context_db_handle(context);

  sqlite3_result_int(context, sqlite3_changes(db));

}

/*

** Implementation of the total_changes() SQL function.  The return value is

** the same as the sqlite3_total_changes() API function.

*/

static void total_changes(

  sqlite3_context *context,

  int arg,

  sqlite3_value **argv

){

  sqlite3 *db = sqlite3_context_db_handle(context);

  sqlite3_result_int(context, sqlite3_total_changes(db));

}

/*

** A structure defining how to do GLOB-style comparisons.

*/

struct compareInfo {

  u8 matchAll;

  u8 matchOne;

  u8 matchSet;

  u8 noCase;

};

/*

** For LIKE and GLOB matching on EBCDIC machines, assume that every

** character is exactly one byte in size.  Also, all characters are

** able to participate in upper-case-to-lower-case mappings in EBCDIC

** whereas only characters less than 0x80 do in ASCII.

*/

#if defined(SQLITE_EBCDIC)

# define sqlite3Utf8Read(A,B,C)  (*(A++))

# define GlogUpperToLower(A)     A = sqlite3UpperToLower[A]

#else

# define GlogUpperToLower(A)     if( A<0x80 ){ A = sqlite3UpperToLower[A]; }

#endif

static const struct compareInfo globInfo = { '*', '?', '[', 0 };

/* The correct SQL-92 behavior is for the LIKE operator to ignore

** case.  Thus  'a' LIKE 'A' would be true. */

static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };

/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator

** is case sensitive causing 'a' LIKE 'A' to be false */

static const struct compareInfo likeInfoAlt = { '%', '_',   0, 0 };

/*

** Compare two UTF-8 strings for equality where the first string can

** potentially be a "glob" expression.  Return true (1) if they

** are the same and false (0) if they are different.

**

** Globbing rules:

**

**      '*'       Matches any sequence of zero or more characters.

**

**      '?'       Matches exactly one character.

**

**     [...]      Matches one character from the enclosed list of

**                characters.

**

**     [^...]     Matches one character not in the enclosed list.

**

** With the [...] and [^...] matching, a ']' character can be included

** in the list by making it the first character after '[' or '^'.  A

** range of characters can be specified using '-'.  Example:

** "[a-z]" matches any single lower-case letter.  To match a '-', make

** it the last character in the list.

**

** This routine is usually quick, but can be N**2 in the worst case.

**

** Hints: to match '*' or '?', put them in "[]".  Like this:

**

**         abc[*]xyz        Matches "abc*xyz" only

*/

static int patternCompare(

  const u8 *zPattern,              /* The glob pattern */

  const u8 *zString,               /* The string to compare against the glob */

  const struct compareInfo *pInfo, /* Information about how to do the compare */

  const int esc                    /* The escape character */

){

  int c, c2;

  int invert;

  int seen;

  u8 matchOne = pInfo->matchOne;

  u8 matchAll = pInfo->matchAll;

  u8 matchSet = pInfo->matchSet;

  u8 noCase = pInfo->noCase; 

  int prevEscape = 0;     /* True if the previous character was 'escape' */

  while( (c = sqlite3Utf8Read(zPattern,0,&zPattern))!=0 ){

    if( !prevEscape && c==matchAll ){

      while( (c=sqlite3Utf8Read(zPattern,0,&zPattern)) == matchAll

               || c == matchOne ){

        if( c==matchOne && sqlite3Utf8Read(zString, 0, &zString)==0 ){

          return 0;

        }

      }

      if( c==0 ){

        return 1;

      }else if( c==esc ){

        c = sqlite3Utf8Read(zPattern, 0, &zPattern);

        if( c==0 ){

          return 0;

        }

      }else if( c==matchSet ){

        assert( esc==0 );         /* This is GLOB, not LIKE */

        assert( matchSet<0x80 );  /* '[' is a single-byte character */

        while( *zString && patternCompare(&zPattern[-1],zString,pInfo,esc)==0 ){

          SQLITE_SKIP_UTF8(zString);

        }

        return *zString!=0;

      }

      while( (c2 = sqlite3Utf8Read(zString,0,&zString))!=0 ){

        if( noCase ){

          GlogUpperToLower(c2);

          GlogUpperToLower(c);

          while( c2 != 0 && c2 != c ){

            c2 = sqlite3Utf8Read(zString, 0, &zString);

            GlogUpperToLower(c2);

          }

        }else{

          while( c2 != 0 && c2 != c ){

            c2 = sqlite3Utf8Read(zString, 0, &zString);

          }

        }

        if( c2==0 ) return 0;

        if( patternCompare(zPattern,zString,pInfo,esc) ) return 1;

      }

      return 0;

    }else if( !prevEscape && c==matchOne ){

      if( sqlite3Utf8Read(zString, 0, &zString)==0 ){

        return 0;

      }

    }else if( c==matchSet ){

      int prior_c = 0;

      assert( esc==0 );    /* This only occurs for GLOB, not LIKE */

      seen = 0;

      invert = 0;

      c = sqlite3Utf8Read(zString, 0, &zString);

      if( c==0 ) return 0;

      c2 = sqlite3Utf8Read(zPattern, 0, &zPattern);

      if( c2=='^' ){

        invert = 1;

        c2 = sqlite3Utf8Read(zPattern, 0, &zPattern);

      }