func.c

sqlite 嵌入式数据库的源码

/*
** 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 1.98 2005/05/24 12:01:02 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#include "vdbeInt.h"
#include "os.h"

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 char *z = sqlite3_value_text(argv[0]);
      for(len=0; *z; z++){ if( (0xc0&*z)!=0x80 ) len++; }
      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 ) iVal = iVal * -1;
      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 * -1.0;
      sqlite3_result_double(context, rVal);
      break;
    }
  }
}

/*
** Implementation of the substr() function
*/
static void substrFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  const char *z;
  const char *z2;
  int i;
  int p1, p2, len;

  assert( argc==3 );
  z = sqlite3_value_text(argv[0]);
  if( z==0 ) return;
  p1 = sqlite3_value_int(argv[1]);
  p2 = sqlite3_value_int(argv[2]);
  for(len=0, z2=z; *z2; z2++){ if( (0xc0&*z2)!=0x80 ) len++; }
  if( p1<0 ){
    p1 += len;
    if( p1<0 ){
      p2 += p1;
      p1 = 0;
    }
  }else if( p1>0 ){
    p1--;
  }
  if( p1+p2>len ){
    p2 = len-p1;
  }
  for(i=0; i<p1 && z[i]; i++){
    if( (z[i]&0xc0)==0x80 ) p1++;
  }
  while( z[i] && (z[i]&0xc0)==0x80 ){ i++; p1++; }
  for(; i<p1+p2 && z[i]; i++){
    if( (z[i]&0xc0)==0x80 ) p2++;
  }
  while( z[i] && (z[i]&0xc0)==0x80 ){ i++; p2++; }
  if( p2<0 ) p2 = 0;
  sqlite3_result_text(context, &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[100];
  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( SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;
  r = sqlite3_value_double(argv[0]);
  sprintf(zBuf,"%.*f",n,r);
  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
}

/*
** Implementation of the upper() and lower() SQL functions.
*/
static void upperFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  unsigned char *z;
  int i;
  if( argc<1 || SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;
  z = sqliteMalloc(sqlite3_value_bytes(argv[0])+1);
  if( z==0 ) return;
  strcpy(z, sqlite3_value_text(argv[0]));
  for(i=0; z[i]; i++){
    z[i] = toupper(z[i]);
  }
  sqlite3_result_text(context, z, -1, SQLITE_TRANSIENT);
  sqliteFree(z);
}
static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  unsigned char *z;
  int i;
  if( argc<1 || SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;
  z = sqliteMalloc(sqlite3_value_bytes(argv[0])+1);
  if( z==0 ) return;
  strcpy(z, sqlite3_value_text(argv[0]));
  for(i=0; z[i]; i++){
    z[i] = tolower(z[i]);
  }
  sqlite3_result_text(context, z, -1, SQLITE_TRANSIENT);
  sqliteFree(z);
}

/*
** 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
){
  int r;
  sqlite3Randomness(sizeof(r), &r);
  sqlite3_result_int(context, r);
}

/*
** 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_user_data(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_user_data(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_user_data(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;
};
static const struct compareInfo globInfo = { '*', '?', '[', 0 };
static const struct compareInfo likeInfo = { '%', '_',   0, 1 };

/*
** X is a pointer to the first byte of a UTF-8 character.  Increment
** X so that it points to the next character.  This only works right
** if X points to a well-formed UTF-8 string.
*/
#define sqliteNextChar(X)  while( (0xc0&*++(X))==0x80 ){}
#define sqliteCharVal(X)   sqlite3ReadUtf8(X)


/*
** 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 */
){
  register int c;
  int invert;
  int seen;
  int c2;
  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 = *zPattern)!=0 ){
    if( !prevEscape && c==matchAll ){
      while( (c=zPattern[1]) == matchAll || c == matchOne ){
        if( c==matchOne ){
          if( *zString==0 ) return 0;
          sqliteNextChar(zString);
        }
        zPattern++;
      }
      if( c && esc && sqlite3ReadUtf8(&zPattern[1])==esc ){
        u8 const *zTemp = &zPattern[1];
        sqliteNextChar(zTemp);
        c = *zTemp;
      }
      if( c==0 ) return 1;
      if( c==matchSet ){
        assert( esc==0 );   /* This is GLOB, not LIKE */
        while( *zString && patternCompare(&zPattern[1],zString,pInfo,esc)==0 ){
          sqliteNextChar(zString);
        }
        return *zString!=0;
      }else{
        while( (c2 = *zString)!=0 ){
          if( noCase ){
            c2 = sqlite3UpperToLower[c2];
            c = sqlite3UpperToLower[c];
            while( c2 != 0 && c2 != c ){ c2 = sqlite3UpperToLower[*++zString]; }
          }else{
            while( c2 != 0 && c2 != c ){ c2 = *++zString; }
          }
          if( c2==0 ) return 0;
          if( patternCompare(&zPattern[1],zString,pInfo,esc) ) return 1;
          sqliteNextChar(zString);
        }
        return 0;
      }
    }else if( !prevEscape && c==matchOne ){
      if( *zString==0 ) return 0;
      sqliteNextChar(zString);
      zPattern++;
    }else if( c==matchSet ){
      int prior_c = 0;
      assert( esc==0 );    /* This only occurs for GLOB, not LIKE */
      seen = 0;
      invert = 0;
      c = sqliteCharVal(zString);
      if( c==0 ) return 0;
      c2 = *++zPattern;
      if( c2=='^' ){ invert = 1; c2 = *++zPattern; }
      if( c2==']' ){
        if( c==']' ) seen = 1;
        c2 = *++zPattern;
      }
      while( (c2 = sqliteCharVal(zPattern))!=0 && c2!=']' ){
        if( c2=='-' && zPattern[1]!=']' && zPattern[1]!=0 && prior_c>0 ){
          zPattern++;
          c2 = sqliteCharVal(zPattern);
          if( c>=prior_c && c<=c2 ) seen = 1;
          prior_c = 0;
        }else if( c==c2 ){
          seen = 1;
          prior_c = c2;
        }else{
          prior_c = c2;
        }
        sqliteNextChar(zPattern);
      }
      if( c2==0 || (seen ^ invert)==0 ) return 0;
      sqliteNextChar(zString);
      zPattern++;
    }else if( esc && !prevEscape && sqlite3ReadUtf8(zPattern)==esc){
      prevEscape = 1;
      sqliteNextChar(zPattern);
    }else{
      if( noCase ){
        if( sqlite3UpperToLower[c] != sqlite3UpperToLower[*zString] ) return 0;
      }else{
        if( c != *zString ) return 0;
      }
      zPattern++;
      zString++;
      prevEscape = 0;
    }
  }
  return *zString==0;
}


/*
** Implementation of the like() SQL function.  This function implements
** the build-in LIKE operator.  The first argument to the function is the
** pattern and the second argument is the string.  So, the SQL statements:
**
**       A LIKE B
**
** is implemented as like(B,A).
**
** If the pointer retrieved by via a call to sqlite3_user_data() is
** not NULL, then this function uses UTF-16. Otherwise UTF-8.
*/
static void likeFunc(
  sqlite3_context *context, 
  int argc, 
  sqlite3_value **argv
){
  const unsigned char *zA = sqlite3_value_text(argv[0]);
  const unsigned char *zB = sqlite3_value_text(argv[1]);
  int escape = 0;
  if( argc==3 ){
    /* The escape character string must consist of a single UTF-8 character.
    ** Otherwise, return an error.
    */
    const unsigned char *zEsc = sqlite3_value_text(argv[2]);
    if( sqlite3utf8CharLen(zEsc, -1)!=1 ){
      sqlite3_result_error(context, 
          "ESCAPE expression must be a single character", -1);
      return;
    }
    escape = sqlite3ReadUtf8(zEsc);
  }
  if( zA && zB ){
    sqlite3_result_int(context, patternCompare(zA, zB, &likeInfo, escape));
  }
}

/*
** Implementation of the glob() SQL function.  This function implements
** the build-in GLOB operator.  The first argument to the function is the
** string and the second argument is the pattern.  So, the SQL statements:
**
**       A GLOB B
**
** is implemented as glob(B,A).
*/
static void globFunc(sqlite3_context *context, int arg, sqlite3_value **argv){
  const unsigned char *zA = sqlite3_value_text(argv[0]);
  const unsigned char *zB = sqlite3_value_text(argv[1]);
  if( zA && zB ){
    sqlite3_result_int(context, patternCompare(zA, zB, &globInfo, 0));
  }
}

/*
** Implementation of the NULLIF(x,y) function.  The result is the first
** argument if the arguments are different.  The result is NULL if the
** arguments are equal to each other.
*/
static void nullifFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  CollSeq *pColl = sqlite3GetFuncCollSeq(context);
  if( sqlite3MemCompare(argv[0], argv[1], pColl)!=0 ){
    sqlite3_result_value(context, argv[0]);
  }
}