vdbe.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

/* Opcode: Integer P1 * P3
**
** The integer value P1 is pushed onto the stack.  If P3 is not zero
** then it is assumed to be a string representation of the same integer.
*/
case OP_Integer: {
  int i = ++p->tos;
  aStack[i].i = pOp->p1;
  aStack[i].flags = STK_Int;
  if( pOp->p3 ){
    zStack[i] = pOp->p3;
    aStack[i].flags |= STK_Str | STK_Static;
    aStack[i].n = strlen(pOp->p3)+1;
  }
  break;
}

/* Opcode: String * * P3
**
** The string value P3 is pushed onto the stack.  If P3==0 then a
** NULL is pushed onto the stack.
*/
case OP_String: {
  int i = ++p->tos;
  char *z;
  z = pOp->p3;
  if( z==0 ){
    zStack[i] = 0;
    aStack[i].n = 0;
    aStack[i].flags = STK_Null;
  }else{
    zStack[i] = z;
    aStack[i].n = strlen(z) + 1;
    aStack[i].flags = STK_Str | STK_Static;
  }
  break;
}

/* Opcode: Pop P1 * *
**
** P1 elements are popped off of the top of stack and discarded.
*/
case OP_Pop: {
  assert( p->tos+1>=pOp->p1 );
  PopStack(p, pOp->p1);
  break;
}

/* Opcode: Dup P1 P2 *
**
** A copy of the P1-th element of the stack 
** is made and pushed onto the top of the stack.
** The top of the stack is element 0.  So the
** instruction "Dup 0 0 0" will make a copy of the
** top of the stack.
**
** If the content of the P1-th element is a dynamically
** allocated string, then a new copy of that string
** is made if P2==0.  If P2!=0, then just a pointer
** to the string is copied.
**
** Also see the Pull instruction.
*/
case OP_Dup: {
  int i = p->tos - pOp->p1;
  int j = ++p->tos;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  memcpy(&aStack[j], &aStack[i], sizeof(aStack[i])-NBFS);
  if( aStack[j].flags & STK_Str ){
    int isStatic = (aStack[j].flags & STK_Static)!=0;
    if( pOp->p2 || isStatic ){
      zStack[j] = zStack[i];
      aStack[j].flags &= ~STK_Dyn;
      if( !isStatic ) aStack[j].flags |= STK_Ephem;
    }else if( aStack[i].n<=NBFS ){
      memcpy(aStack[j].z, zStack[i], aStack[j].n);
      zStack[j] = aStack[j].z;
      aStack[j].flags &= ~(STK_Static|STK_Dyn|STK_Ephem);
    }else{
      zStack[j] = sqliteMallocRaw( aStack[j].n );
      if( zStack[j]==0 ) goto no_mem;
      memcpy(zStack[j], zStack[i], aStack[j].n);
      aStack[j].flags &= ~(STK_Static|STK_Ephem);
      aStack[j].flags |= STK_Dyn;
    }
  }
  break;
}

/* Opcode: Pull P1 * *
**
** The P1-th element is removed from its current location on 
** the stack and pushed back on top of the stack.  The
** top of the stack is element 0, so "Pull 0 0 0" is
** a no-op.  "Pull 1 0 0" swaps the top two elements of
** the stack.
**
** See also the Dup instruction.
*/
case OP_Pull: {
  int from = p->tos - pOp->p1;
  int to = p->tos;
  int i;
  Stack ts;
  char *tz;
  VERIFY( if( from<0 ) goto not_enough_stack; )
  Deephemeralize(p, from);
  ts = aStack[from];
  tz = zStack[from];
  Deephemeralize(p, to);
  for(i=from; i<to; i++){
    Deephemeralize(p, i+1);
    aStack[i] = aStack[i+1];
    assert( (aStack[i].flags & STK_Ephem)==0 );
    if( aStack[i].flags & (STK_Dyn|STK_Static) ){
      zStack[i] = zStack[i+1];
    }else{
      zStack[i] = aStack[i].z;
    }
  }
  aStack[to] = ts;
  assert( (aStack[to].flags & STK_Ephem)==0 );
  if( aStack[to].flags & (STK_Dyn|STK_Static) ){
    zStack[to] = tz;
  }else{
    zStack[to] = aStack[to].z;
  }
  break;
}

/* Opcode: Push P1 * *
**
** Overwrite the value of the P1-th element down on the
** stack (P1==0 is the top of the stack) with the value
** of the top of the stack.  Then pop the top of the stack.
*/
case OP_Push: {
  int from = p->tos;
  int to = p->tos - pOp->p1;

  VERIFY( if( to<0 ) goto not_enough_stack; )
  if( aStack[to].flags & STK_Dyn ){
    sqliteFree(zStack[to]);
  }
  Deephemeralize(p, from);
  aStack[to] = aStack[from];
  if( aStack[to].flags & (STK_Dyn|STK_Static|STK_Ephem) ){
    zStack[to] = zStack[from];
  }else{
    zStack[to] = aStack[to].z;
  }
  aStack[from].flags = 0;
  p->tos--;
  break;
}

/* Opcode: ColumnName P1 * P3
**
** P3 becomes the P1-th column name (first is 0).  An array of pointers
** to all column names is passed as the 4th parameter to the callback.
*/
case OP_ColumnName: {
  assert( pOp->p1>=0 && pOp->p1<p->nOp );
  p->azColName[pOp->p1] = pOp->p3;
  p->nCallback = 0;
  break;
}

/* Opcode: Callback P1 * *
**
** Pop P1 values off the stack and form them into an array.  Then
** invoke the callback function using the newly formed array as the
** 3rd parameter.
*/
case OP_Callback: {
  int i = p->tos - pOp->p1 + 1;
  int j;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  for(j=i; j<=p->tos; j++){
    if( aStack[j].flags & STK_Null ){
      zStack[j] = 0;
    }else{
      Stringify(p, j);
    }
  }
  zStack[p->tos+1] = 0;
  if( p->xCallback==0 ){
    p->azResColumn = &zStack[i];
    p->nResColumn = pOp->p1;
    p->popStack = pOp->p1;
    p->pc = pc + 1;
    return SQLITE_ROW;
  }
  if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
  if( p->xCallback(p->pCbArg, pOp->p1, &zStack[i], p->azColName)!=0 ){
    rc = SQLITE_ABORT;
  }
  if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
  p->nCallback++;
  PopStack(p, pOp->p1);
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

/* Opcode: NullCallback P1 * *
**
** Invoke the callback function once with the 2nd argument (the
** number of columns) equal to P1 and with the 4th argument (the
** names of the columns) set according to prior OP_ColumnName
** instructions.  This is all like the regular
** OP_Callback or OP_SortCallback opcodes.  But the 3rd argument
** which normally contains a pointer to an array of pointers to
** data is NULL.
**
** The callback is only invoked if there have been no prior calls
** to OP_Callback or OP_SortCallback.
**
** This opcode is used to report the number and names of columns
** in cases where the result set is empty.
*/
case OP_NullCallback: {
  if( p->nCallback==0 && p->xCallback!=0 ){
    if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
    if( p->xCallback(p->pCbArg, pOp->p1, 0, p->azColName)!=0 ){
      rc = SQLITE_ABORT;
    }
    if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
    p->nCallback++;
    if( sqlite_malloc_failed ) goto no_mem;
  }
  p->nResColumn = pOp->p1;
  break;
}

/* Opcode: Concat P1 P2 P3
**
** Look at the first P1 elements of the stack.  Append them all 
** together with the lowest element first.  Use P3 as a separator.  
** Put the result on the top of the stack.  The original P1 elements
** are popped from the stack if P2==0 and retained if P2==1.  If
** any element of the stack is NULL, then the result is NULL.
**
** If P3 is NULL, then use no separator.  When P1==1, this routine
** makes a copy of the top stack element into memory obtained
** from sqliteMalloc().
*/
case OP_Concat: {
  char *zNew;
  int nByte;
  int nField;
  int i, j;
  char *zSep;
  int nSep;

  nField = pOp->p1;
  zSep = pOp->p3;
  if( zSep==0 ) zSep = "";
  nSep = strlen(zSep);
  VERIFY( if( p->tos+1<nField ) goto not_enough_stack; )
  nByte = 1 - nSep;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( aStack[i].flags & STK_Null ){
      nByte = -1;
      break;
    }else{
      Stringify(p, i);
      nByte += aStack[i].n - 1 + nSep;
    }
  }
  if( nByte<0 ){
    if( pOp->p2==0 ) PopStack(p, nField);
    p->tos++;
    aStack[p->tos].flags = STK_Null;
    zStack[p->tos] = 0;
    break;
  }
  zNew = sqliteMallocRaw( nByte );
  if( zNew==0 ) goto no_mem;
  j = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & STK_Null)==0 ){
      memcpy(&zNew[j], zStack[i], aStack[i].n-1);
      j += aStack[i].n-1;
    }
    if( nSep>0 && i<p->tos ){
      memcpy(&zNew[j], zSep, nSep);
      j += nSep;
    }
  }
  zNew[j] = 0;
  if( pOp->p2==0 ) PopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  aStack[p->tos].flags = STK_Str|STK_Dyn;
  zStack[p->tos] = zNew;
  break;
}

/* Opcode: Add * * *
**
** Pop the top two elements from the stack, add them together,
** and push the result back onto the stack.  If either element
** is a string then it is converted to a double using the atof()
** function before the addition.
** If either operand is NULL, the result is NULL.
*/
/* Opcode: Multiply * * *
**
** Pop the top two elements from the stack, multiply them together,
** and push the result back onto the stack.  If either element
** is a string then it is converted to a double using the atof()
** function before the multiplication.
** If either operand is NULL, the result is NULL.
*/
/* Opcode: Subtract * * *
**
** Pop the top two elements from the stack, subtract the
** first (what was on top of the stack) from the second (the
** next on stack)
** and push the result back onto the stack.  If either element
** is a string then it is converted to a double using the atof()
** function before the subtraction.
** If either operand is NULL, the result is NULL.
*/
/* Opcode: Divide * * *
**
** Pop the top two elements from the stack, divide the
** first (what was on top of the stack) from the second (the
** next on stack)
** and push the result back onto the stack.  If either element
** is a string then it is converted to a double using the atof()
** function before the division.  Division by zero returns NULL.
** If either operand is NULL, the result is NULL.
*/
/* Opcode: Remainder * * *
**
** Pop the top two elements from the stack, divide the
** first (what was on top of the stack) from the second (the
** next on stack)
** and push the remainder after division onto the stack.  If either element
** is a string then it is converted to a double using the atof()
** function before the division.  Division by zero returns NULL.
** If either operand is NULL, the result is NULL.
*/
case OP_Add:
case OP_Subtract:
case OP_Multiply:
case OP_Divide:
case OP_Remainder: {
  int tos = p->tos;
  int nos = tos - 1;
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  if( ((aStack[tos].flags | aStack[nos].flags) & STK_Null)!=0 ){
    POPSTACK;
    Release(p, nos);
    aStack[nos].flags = STK_Null;
  }else if( (aStack[tos].flags & aStack[nos].flags & STK_Int)==STK_Int ){
    int a, b;
    a = aStack[tos].i;
    b = aStack[nos].i;
    switch( pOp->opcode ){
      case OP_Add:         b += a;       break;
      case OP_Subtract:    b -= a;       break;
      case OP_Multiply:    b *= a;       break;
      case OP_Divide: {
        if( a==0 ) goto divide_by_zero;
        b /= a;
        break;
      }
      default: {
        if( a==0 ) goto divide_by_zero;
        b %= a;
        break;
      }
    }
    POPSTACK;
    Release(p, nos);
    aStack[nos].i = b;
    aStack[nos].flags = STK_Int;
  }else{
    double a, b;
    Realify(p, tos);
    Realify(p, nos);
    a = aStack[tos].r;
    b = aStack[nos].r;
    switch( pOp->opcode ){
      case OP_Add:         b += a;       break;
      case OP_Subtract:    b -= a;       break;
      case OP_Multiply:    b *= a;       break;
      case OP_Divide: {
        if( a==0.0 ) goto divide_by_zero;
        b /= a;
        break;
      }
      default: {
        int ia = (int)a;
        int ib = (int)b;
        if( ia==0.0 ) goto divide_by_zero;
        b = ib % ia;
        break;
      }
    }
    POPSTACK;
    Release(p, nos);
    aStack[nos].r = b;
    aStack[nos].flags = STK_Real;
  }
  break;

divide_by_zero:
  PopStack(p, 2);
  p->tos = nos;
  aStack[nos].flags = STK_Null;
  break;
}

/* Opcode: Function P1 * P3
**
** Invoke a user function (P3 is a pointer to a Function structure that
** defines the function) with P1 string arguments taken from the stack.
** Pop all arguments from the stack and push back the result.
**
** See also: AggFunc
*/
case OP_Function: {
  int n, i;
  sqlite_func ctx;

  n = pOp->p1;
  VERIFY( if( n<0 ) goto bad_instruction; )
  VERIFY( if( p->tos+1<n ) goto not