util.c

SQLite 2.8.6 源代码,用来在Linux/Unix/Windows上编译安装.它是一个小型的数据库,但是非常好用,速度也快,一般的数据库查询之类的操作据统计比MySQL,PostgreSQL

    nByte += n;
  }
  va_end(ap);
  sqliteFree(*pz);
  *pz = zResult = sqliteMallocRaw( nByte + 1 );
  if( zResult==0 ) return;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    n = va_arg(ap, int);
    if( n<=0 ) n = strlen(z);
    strncpy(zResult, z, n);
    zResult += n;
  }
  *zResult = 0;
#ifdef MEMORY_DEBUG
#if MEMORY_DEBUG>1
  fprintf(stderr,"string at 0x%x is %s\n", (int)*pz, *pz);
#endif
#endif
  va_end(ap);
}

/*
** Add an error message to pParse->zErrMsg and increment pParse->nErr.
** The following formatting characters are allowed:
**
**      %s      Insert a string
**      %z      A string that should be freed after use
**      %d      Insert an integer
**      %T      Insert a token
**      %S      Insert the first element of a SrcList
*/
void sqliteErrorMsg(Parse *pParse, const char *zFormat, ...){
  va_list ap;
  int nByte;
  int i, j;
  char *z;
  static char zNull[] = "NULL";

  pParse->nErr++;
  nByte = 1 + strlen(zFormat);
  va_start(ap, zFormat);
  for(i=0; zFormat[i]; i++){
    if( zFormat[i]!='%' || zFormat[i+1]==0 ) continue;
    i++;
    switch( zFormat[i] ){
      case 'd': {
        (void)va_arg(ap, int);
        nByte += 20;
        break;
      }
      case 'z':
      case 's': {
        char *z2 = va_arg(ap, char*);
        if( z2==0 ) z2 = zNull;
        nByte += strlen(z2);
        break;
      }
      case 'T': {
        Token *p = va_arg(ap, Token*);
        nByte += p->n;
        break;
      }
      case 'S': {
        SrcList *p = va_arg(ap, SrcList*);
        int k = va_arg(ap, int);
        assert( p->nSrc>k && k>=0 );
        nByte += strlen(p->a[k].zName);
        if( p->a[k].zDatabase && p->a[k].zDatabase[0] ){
          nByte += strlen(p->a[k].zDatabase)+1;
        }
        break;
      }
      default: {
        nByte++;
        break;
      }
    }
  }
  va_end(ap);
  z = sqliteMalloc( nByte );
  if( z==0 ) return;
  sqliteFree(pParse->zErrMsg);
  pParse->zErrMsg = z;
  va_start(ap, zFormat);
  for(i=j=0; zFormat[i]; i++){
    if( zFormat[i]!='%' || zFormat[i+1]==0 ) continue;
    if( i>j ){
      memcpy(z, &zFormat[j], i-j);
      z += i-j;
    }
    j = i+2;
    i++;
    switch( zFormat[i] ){
      case 'd': {
        int x = va_arg(ap, int);
        sprintf(z, "%d", x);
        z += strlen(z);
        break;
      }
      case 'z':
      case 's': {
        int len;
        char *z2 = va_arg(ap, char*);
        if( z2==0 ) z2 = zNull;
        len = strlen(z2);
        memcpy(z, z2, len);
        z += len;
        if( zFormat[i]=='z' && z2!=zNull ){
          sqliteFree(z2);
        }
        break;
      }
      case 'T': {
        Token *p = va_arg(ap, Token*);
        memcpy(z, p->z, p->n);
        z += p->n;
        break;
      }
      case 'S': {
        int len;
        SrcList *p = va_arg(ap, SrcList*);
        int k = va_arg(ap, int);
        assert( p->nSrc>k && k>=0 );
        if( p->a[k].zDatabase && p->a[k].zDatabase[0] ){
          len = strlen(p->a[k].zDatabase);
          memcpy(z, p->a[k].zDatabase, len);
          z += len;
          *(z++) = '.';
        }
        len = strlen(p->a[k].zName);
        memcpy(z, p->a[k].zName, len);
        z += len;
        break;
      }
      default: {
        *(z++) = zFormat[i];
        break;
      }
    }
  }
  va_end(ap);
  if( i>j ){
    memcpy(z, &zFormat[j], i-j);
    z += i-j;
  }
  assert( (z - pParse->zErrMsg) < nByte );
  *z = 0;
}

/*
** Convert an SQL-style quoted string into a normal string by removing
** the quote characters.  The conversion is done in-place.  If the
** input does not begin with a quote character, then this routine
** is a no-op.
**
** 2002-Feb-14: This routine is extended to remove MS-Access style
** brackets from around identifers.  For example:  "[a-b-c]" becomes
** "a-b-c".
*/
void sqliteDequote(char *z){
  int quote;
  int i, j;
  if( z==0 ) return;
  quote = z[0];
  switch( quote ){
    case '\'':  break;
    case '"':   break;
    case '[':   quote = ']';  break;
    default:    return;
  }
  for(i=1, j=0; z[i]; i++){
    if( z[i]==quote ){
      if( z[i+1]==quote ){
        z[j++] = quote;
        i++;
      }else{
        z[j++] = 0;
        break;
      }
    }else{
      z[j++] = z[i];
    }
  }
}

/* An array to map all upper-case characters into their corresponding
** lower-case character. 
*/
static unsigned char UpperToLower[] = {
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17,
     18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
     36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
     54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 97, 98, 99,100,101,102,103,
    104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,
    122, 91, 92, 93, 94, 95, 96, 97, 98, 99,100,101,102,103,104,105,106,107,
    108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
    126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
    144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,
    162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,
    180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,
    198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
    216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
    234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
    252,253,254,255
};

/*
** This function computes a hash on the name of a keyword.
** Case is not significant.
*/
int sqliteHashNoCase(const char *z, int n){
  int h = 0;
  if( n<=0 ) n = strlen(z);
  while( n > 0  ){
    h = (h<<3) ^ h ^ UpperToLower[(unsigned char)*z++];
    n--;
  }
  return h & 0x7fffffff;
}

/*
** Some systems have stricmp().  Others have strcasecmp().  Because
** there is no consistency, we will define our own.
*/
int sqliteStrICmp(const char *zLeft, const char *zRight){
  register unsigned char *a, *b;
  a = (unsigned char *)zLeft;
  b = (unsigned char *)zRight;
  while( *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
  return *a - *b;
}
int sqliteStrNICmp(const char *zLeft, const char *zRight, int N){
  register unsigned char *a, *b;
  a = (unsigned char *)zLeft;
  b = (unsigned char *)zRight;
  while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
  return N<0 ? 0 : *a - *b;
}

/*
** Return TRUE if z is a pure numeric string.  Return FALSE if the
** string contains any character which is not part of a number.
**
** Am empty string is considered non-numeric.
*/
int sqliteIsNumber(const char *z){
  if( *z=='-' || *z=='+' ) z++;
  if( !isdigit(*z) ){
    return 0;
  }
  z++;
  while( isdigit(*z) ){ z++; }
  if( *z=='.' ){
    z++;
    if( !isdigit(*z) ) return 0;
    while( isdigit(*z) ){ z++; }
  }
  if( *z=='e' || *z=='E' ){
    z++;
    if( *z=='+' || *z=='-' ) z++;
    if( !isdigit(*z) ) return 0;
    while( isdigit(*z) ){ z++; }
  }
  return *z==0;
}

/* This comparison routine is what we use for comparison operations
** between numeric values in an SQL expression.  "Numeric" is a little
** bit misleading here.  What we mean is that the strings have a
** type of "numeric" from the point of view of SQL.  The strings
** do not necessarily contain numbers.  They could contain text.
**
** If the input strings both look like actual numbers then they
** compare in numerical order.  Numerical strings are always less 
** than non-numeric strings so if one input string looks like a
** number and the other does not, then the one that looks like
** a number is the smaller.  Non-numeric strings compare in 
** lexigraphical order (the same order as strcmp()).
*/
int sqliteCompare(const char *atext, const char *btext){
  int result;
  int isNumA, isNumB;
  if( atext==0 ){
    return -1;
  }else if( btext==0 ){
    return 1;
  }
  isNumA = sqliteIsNumber(atext);
  isNumB = sqliteIsNumber(btext);
  if( isNumA ){
    if( !isNumB ){
      result = -1;
    }else{
      double rA, rB;
      rA = atof(atext);
      rB = atof(btext);
      if( rA<rB ){
        result = -1;
      }else if( rA>rB ){
        result = +1;
      }else{
        result = 0;
      }
    }
  }else if( isNumB ){
    result = +1;
  }else {
    result = strcmp(atext, btext);
  }
  return result; 
}

/*
** This routine is used for sorting.  Each key is a list of one or more
** null-terminated elements.  The list is terminated by two nulls in
** a row.  For example, the following text is a key with three elements
**
**            Aone\000Dtwo\000Athree\000\000
**
** All elements begin with one of the characters "+-AD" and end with "\000"
** with zero or more text elements in between.  Except, NULL elements
** consist of the special two-character sequence "N\000".
**
** Both arguments will have the same number of elements.  This routine
** returns negative, zero, or positive if the first argument is less
** than, equal to, or greater than the first.  (Result is a-b).
**
** Each element begins with one of the characters "+", "-", "A", "D".
** This character determines the sort order and collating sequence:
**
**     +      Sort numerically in ascending order
**     -      Sort numerically in descending order
**     A      Sort as strings in ascending order
**     D      Sort as strings in descending order.
**
** For the "+" and "-" sorting, pure numeric strings (strings for which the
** isNum() function above returns TRUE) always compare less than strings
** that are not pure numerics.  Non-numeric strings compare in memcmp()
** order.  This is the same sort order as the sqliteCompare() function
** above generates.
**
** The last point is a change from version 2.6.3 to version 2.7.0.  In
** version 2.6.3 and earlier, substrings of digits compare in numerical 
** and case was used only to break a tie.
**
** Elements that begin with 'A' or 'D' compare in memcmp() order regardless
** of whether or not they look like a number.
**
** Note that the sort order imposed by the rules above is the same
** from the ordering defined by the "<", "<=", ">", and ">=" operators
** of expressions and for indices.  This was not the case for version
** 2.6.3 and earlier.
*/
int sqliteSortCompare(const char *a, const char *b){
  int res = 0;
  int isNumA, isNumB;
  int dir = 0;

  while( res==0 && *a && *b ){
    if( a[0]=='N' || b[0]=='N' ){
      if( a[0]==b[0] ){
        a += 2;
        b += 2;
        continue;
      }
      if( a[0]=='N' ){
        dir = b[0];
        res = -1;
      }else{
        dir = a[0];
        res = +1;
      }
      break;
    }
    assert( a[0]==b[0] );
    if( (dir=a[0])=='A' || a[0]=='D' ){
      res = strcmp(&a[1],&b[1]);
      if( res ) break;
    }else{
      isNumA = sqliteIsNumber(&a[1]);
      isNumB = sqliteIsNumber(&b[1]);
      if( isNumA ){
        double rA, rB;
        if( !isNumB ){
          res = -1;
          break;
        }
        rA = atof(&a[1]);