vdbe.c

一个小型嵌入式数据库SQLite的源码,C语言

**
** Pop the top two elements from the stack.  Convert both elements
** to integers.  Push back onto the stack the second element shifted
** left by N bits where N is the top element on the stack.
** If either operand is NULL, the result is NULL.
*/
/* Opcode: ShiftRight * * *
**
** Pop the top two elements from the stack.  Convert both elements
** to integers.  Push back onto the stack the second element shifted
** right by N bits where N is the top element on the stack.
** If either operand is NULL, the result is NULL.
*/
case OP_BitAnd:                 /* same as TK_BITAND, no-push */
case OP_BitOr:                  /* same as TK_BITOR, no-push */
case OP_ShiftLeft:              /* same as TK_LSHIFT, no-push */
case OP_ShiftRight: {           /* same as TK_RSHIFT, no-push */
  Mem *pNos = &pTos[-1];
  i64 a, b;

  assert( pNos>=p->aStack );
  if( (pTos->flags | pNos->flags) & MEM_Null ){
    popStack(&pTos, 2);
    pTos++;
    pTos->flags = MEM_Null;
    break;
  }
  a = sqlite3VdbeIntValue(pNos);
  b = sqlite3VdbeIntValue(pTos);
  switch( pOp->opcode ){
    case OP_BitAnd:      a &= b;     break;
    case OP_BitOr:       a |= b;     break;
    case OP_ShiftLeft:   a <<= b;    break;
    case OP_ShiftRight:  a >>= b;    break;
    default:   /* CANT HAPPEN */     break;
  }
  Release(pTos);
  pTos--;
  Release(pTos);
  pTos->i = a;
  pTos->flags = MEM_Int;
  break;
}

/* Opcode: AddImm  P1 * *
** 
** Add the value P1 to whatever is on top of the stack.  The result
** is always an integer.
**
** To force the top of the stack to be an integer, just add 0.
*/
case OP_AddImm: {            /* no-push */
  assert( pTos>=p->aStack );
  sqlite3VdbeMemIntegerify(pTos);
  pTos->i += pOp->p1;
  break;
}

/* Opcode: ForceInt P1 P2 *
**
** Convert the top of the stack into an integer.  If the current top of
** the stack is not numeric (meaning that is is a NULL or a string that
** does not look like an integer or floating point number) then pop the
** stack and jump to P2.  If the top of the stack is numeric then
** convert it into the least integer that is greater than or equal to its
** current value if P1==0, or to the least integer that is strictly
** greater than its current value if P1==1.
*/
case OP_ForceInt: {            /* no-push */
  i64 v;
  assert( pTos>=p->aStack );
  applyAffinity(pTos, SQLITE_AFF_NUMERIC, encoding);
  if( (pTos->flags & (MEM_Int|MEM_Real))==0 ){
    Release(pTos);
    pTos--;
    pc = pOp->p2 - 1;
    break;
  }
  if( pTos->flags & MEM_Int ){
    v = pTos->i + (pOp->p1!=0);
  }else{
    /* FIX ME:  should this not be assert( pTos->flags & MEM_Real ) ??? */
    sqlite3VdbeMemRealify(pTos);
    v = (int)pTos->r;
    if( pTos->r>(double)v ) v++;
    if( pOp->p1 && pTos->r==(double)v ) v++;
  }
  Release(pTos);
  pTos->i = v;
  pTos->flags = MEM_Int;
  break;
}

/* Opcode: MustBeInt P1 P2 *
** 
** Force the top of the stack to be an integer.  If the top of the
** stack is not an integer and cannot be converted into an integer
** with out data loss, then jump immediately to P2, or if P2==0
** raise an SQLITE_MISMATCH exception.
**
** If the top of the stack is not an integer and P2 is not zero and
** P1 is 1, then the stack is popped.  In all other cases, the depth
** of the stack is unchanged.
*/
case OP_MustBeInt: {            /* no-push */
  assert( pTos>=p->aStack );
  applyAffinity(pTos, SQLITE_AFF_NUMERIC, encoding);
  if( (pTos->flags & MEM_Int)==0 ){
    if( pOp->p2==0 ){
      rc = SQLITE_MISMATCH;
      goto abort_due_to_error;
    }else{
      if( pOp->p1 ) popStack(&pTos, 1);
      pc = pOp->p2 - 1;
    }
  }else{
    Release(pTos);
    pTos->flags = MEM_Int;
  }
  break;
}

/* Opcode: RealAffinity * * *
**
** If the top of the stack is an integer, convert it to a real value.
**
** This opcode is used when extracting information from a column that
** has REAL affinity.  Such column values may still be stored as
** integers, for space efficiency, but after extraction we want them
** to have only a real value.
*/
case OP_RealAffinity: {                  /* no-push */
  assert( pTos>=p->aStack );
  if( pTos->flags & MEM_Int ){
    sqlite3VdbeMemRealify(pTos);
  }
  break;
}

#ifndef SQLITE_OMIT_CAST
/* Opcode: ToText * * *
**
** Force the value on the top of the stack to be text.
** If the value is numeric, convert it to a string using the
** equivalent of printf().  Blob values are unchanged and
** are afterwards simply interpreted as text.
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_ToText: {                  /* same as TK_TO_TEXT, no-push */
  assert( pTos>=p->aStack );
  if( pTos->flags & MEM_Null ) break;
  assert( MEM_Str==(MEM_Blob>>3) );
  pTos->flags |= (pTos->flags&MEM_Blob)>>3;
  applyAffinity(pTos, SQLITE_AFF_TEXT, encoding);
  assert( pTos->flags & MEM_Str );
  pTos->flags &= ~(MEM_Int|MEM_Real|MEM_Blob);
  break;
}

/* Opcode: ToBlob * * *
**
** Force the value on the top of the stack to be a BLOB.
** If the value is numeric, convert it to a string first.
** Strings are simply reinterpreted as blobs with no change
** to the underlying data.
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_ToBlob: {                  /* same as TK_TO_BLOB, no-push */
  assert( pTos>=p->aStack );
  if( pTos->flags & MEM_Null ) break;
  if( (pTos->flags & MEM_Blob)==0 ){
    applyAffinity(pTos, SQLITE_AFF_TEXT, encoding);
    assert( pTos->flags & MEM_Str );
    pTos->flags |= MEM_Blob;
  }
  pTos->flags &= ~(MEM_Int|MEM_Real|MEM_Str);
  break;
}

/* Opcode: ToNumeric * * *
**
** Force the value on the top of the stack to be numeric (either an
** integer or a floating-point number.)
** If the value is text or blob, try to convert it to an using the
** equivalent of atoi() or atof() and store 0 if no such conversion 
** is possible.
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_ToNumeric: {                  /* same as TK_TO_NUMERIC, no-push */
  assert( pTos>=p->aStack );
  if( (pTos->flags & MEM_Null)==0 ){
    sqlite3VdbeMemNumerify(pTos);
  }
  break;
}
#endif /* SQLITE_OMIT_CAST */

/* Opcode: ToInt * * *
**
** Force the value on the top of the stack to be an integer.  If
** The value is currently a real number, drop its fractional part.
** If the value is text or blob, try to convert it to an integer using the
** equivalent of atoi() and store 0 if no such conversion is possible.
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_ToInt: {                  /* same as TK_TO_INT, no-push */
  assert( pTos>=p->aStack );
  if( (pTos->flags & MEM_Null)==0 ){
    sqlite3VdbeMemIntegerify(pTos);
  }
  break;
}

#ifndef SQLITE_OMIT_CAST
/* Opcode: ToReal * * *
**
** Force the value on the top of the stack to be a floating point number.
** If The value is currently an integer, convert it.
** If the value is text or blob, try to convert it to an integer using the
** equivalent of atoi() and store 0 if no such conversion is possible.
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_ToReal: {                  /* same as TK_TO_REAL, no-push */
  assert( pTos>=p->aStack );
  if( (pTos->flags & MEM_Null)==0 ){
    sqlite3VdbeMemRealify(pTos);
  }
  break;
}
#endif /* SQLITE_OMIT_CAST */

/* Opcode: Eq P1 P2 P3
**
** Pop the top two elements from the stack.  If they are equal, then
** jump to instruction P2.  Otherwise, continue to the next instruction.
**
** If the 0x100 bit of P1 is true and either operand is NULL then take the
** jump.  If the 0x100 bit of P1 is clear then fall thru if either operand
** is NULL.
**
** If the 0x200 bit of P1 is set and either operand is NULL then
** both operands are converted to integers prior to comparison.
** NULL operands are converted to zero and non-NULL operands are
** converted to 1.  Thus, for example, with 0x200 set,  NULL==NULL is true
** whereas it would normally be NULL.  Similarly,  NULL==123 is false when
** 0x200 is set but is NULL when the 0x200 bit of P1 is clear.
**
** The least significant byte of P1 (mask 0xff) must be an affinity character -
** SQLITE_AFF_TEXT, SQLITE_AFF_INTEGER, and so forth. An attempt is made 
** to coerce both values
** according to the affinity before the comparison is made. If the byte is
** 0x00, then numeric affinity is used.
**
** Once any conversions have taken place, and neither value is NULL, 
** the values are compared. If both values are blobs, or both are text,
** then memcmp() is used to determine the results of the comparison. If
** both values are numeric, then a numeric comparison is used. If the
** two values are of different types, then they are inequal.
**
** If P2 is zero, do not jump.  Instead, push an integer 1 onto the
** stack if the jump would have been taken, or a 0 if not.  Push a
** NULL if either operand was NULL.
**
** If P3 is not NULL it is a pointer to a collating sequence (a CollSeq
** structure) that defines how to compare text.
*/
/* Opcode: Ne P1 P2 P3
**
** This works just like the Eq opcode except that the jump is taken if
** the operands from the stack are not equal.  See the Eq opcode for
** additional information.
*/
/* Opcode: Lt P1 P2 P3
**
** This works just like the Eq opcode except that the jump is taken if
** the 2nd element down on the stack is less than the top of the stack.
** See the Eq opcode for additional information.
*/
/* Opcode: Le P1 P2 P3
**
** This works just like the Eq opcode except that the jump is taken if
** the 2nd element down on the stack is less than or equal to the
** top of the stack.  See the Eq opcode for additional information.
*/
/* Opcode: Gt P1 P2 P3
**
** This works just like the Eq opcode except that the jump is taken if
** the 2nd element down on the stack is greater than the top of the stack.
** See the Eq opcode for additional information.
*/
/* Opcode: Ge P1 P2 P3
**
** This works just like the Eq opcode except that the jump is taken if
** the 2nd element down on the stack is greater than or equal to the
** top of the stack.  See the Eq opcode for additional information.
*/
case OP_Eq:               /* same as TK_EQ, no-push */
case OP_Ne:               /* same as TK_NE, no-push */
case OP_Lt:               /* same as TK_LT, no-push */
case OP_Le:               /* same as TK_LE, no-push */
case OP_Gt:               /* same as TK_GT, no-push */
case OP_Ge: {             /* same as TK_GE, no-push */
  Mem *pNos;
  int flags;
  int res;
  char affinity;

  pNos = &pTos[-1];
  flags = pTos->flags|pNos->flags;

  /* If either value is a NULL P2 is not zero, take the jump if the least
  ** significant byte of P1 is true. If P2 is zero, then push a NULL onto
  ** the stack.
  */
  if( flags&MEM_Null ){
    if( (pOp->p1 & 0x200)!=0 ){
      /* The 0x200 bit of P1 means, roughly "do not treat NULL as the
      ** magic SQL value it normally is - treat it as if it were another
      ** integer".
      **
      ** With 0x200 set, if either operand is NULL then both operands
      ** are converted to integers prior to being passed down into the
      ** normal comparison logic below.  NULL operands are converted to
      ** zero and non-NULL operands are converted to 1.  Thus, for example,
      ** with 0x200 set,  NULL==NULL is true whereas it would normally
      ** be NULL.  Similarly,  NULL!=123 is true.
      */
      sqlite3VdbeMemSetInt64(pTos, (pTos->flags & MEM_Null)==0);
      sqlite3VdbeMemSetInt64(pNos, (pNos->flags & MEM_Null)==0);
    }else{
      /* If the 0x200 bit of P1 is clear and either operand is NULL then
      ** the result is always NULL.  The jump is taken if the 0x100 bit
      ** of P1 is set.
      */
      popStack(&pTos, 2);
      if( pOp->p2 ){
        if( pOp->p1 & 0x100 ){
          pc = pOp->p2-1;
        }
      }else{
        pTos++;
        pTos->flags = MEM_Null;
      }
      break;
    }
  }

  affinity = pOp->p1 & 0xFF;
  if( affinity ){
    applyAffinity(pNos, affinity, encoding);
    applyAffinity(pTos, affinity, encoding);
  }

  assert( pOp->p3type==P3_COLLSEQ || pOp->p3==0 );
  res = sqlite3MemCompare(pNos, pTos, (CollSeq*)pOp->p3);
  switch( pOp->opcode ){
    case OP_Eq:    res = res==0;     break;
    case OP_Ne:    res = res!=0;     break;
    case OP_Lt:    res = res<0;      break;
    case OP_Le:    res = res<=0;     break;
    case OP_Gt:    res = res>0;      break;
    default:       res = res>=0;     break;
  }

  popStack(&pTos, 2);
  if( pOp->p2 ){
    if( res ){
      pc = pOp->p2-1;
    }
  }else{
    pTos++;
    pTos->flags = MEM_Int;
    pTos->i = res;
  }
  break;
}

/* Opcode: And * * *
**
** Pop two values off the stack.  Take the logical AND of the
** two values and push the resulting boolean value back onto the
** stack. 
*/
/* Opcode: Or * * *
**
** Pop two values off the stack.  Take the logical OR of the
** two values and push the resulting boolean value back onto the
** stack. 
*/
case OP_And:              /* same as TK_AND, no-push */
case OP_Or: {             /* same as TK_OR, no-push */
  Mem *pNos = &pTos[-1];
  int v1, v2;    /* 0==TRUE, 1==FALSE, 2==UNKNOWN or NULL */

  assert( pNos>=p->aStack );
  if( pTos->flags & MEM_Null ){
    v1 = 2;
  }else{
    sqlite3VdbeMemIntegerify(pTos);
    v1 = pTos->i==0;
  }
  if( pNos->flags & MEM_Null ){
    v2 = 2;
  }else{
    sqlite3VdbeMemIntegerify(pNos);
    v2 = pNos->i==0;
  }
  if( pOp->opcode==OP_And ){
    static const unsigned char and_logic[] = { 0, 1, 2, 1, 1, 1, 2, 1, 2 };
    v1 = and_logic[v1*3+v2];
  }else{
    static const unsigned char or_logic[] = { 0, 0, 0, 0, 1, 2, 0, 2, 2 };
    v1 = or_logic[v1*3+v2];
  }