expr.c

sqlite 嵌入式数据库的源码

      break;
    }
#ifndef SQLITE_OMIT_TRIGGER
    case TK_RAISE: {
      if( !pParse->trigStack ){
        sqlite3ErrorMsg(pParse,
                       "RAISE() may only be used within a trigger-program");
	return;
      }
      if( pExpr->iColumn!=OE_Ignore ){
         assert( pExpr->iColumn==OE_Rollback ||
                 pExpr->iColumn == OE_Abort ||
                 pExpr->iColumn == OE_Fail );
         sqlite3VdbeOp3(v, OP_Halt, SQLITE_CONSTRAINT, pExpr->iColumn,
                        pExpr->token.z, pExpr->token.n);
         sqlite3VdbeDequoteP3(v, -1);
      } else {
         assert( pExpr->iColumn == OE_Ignore );
         sqlite3VdbeAddOp(v, OP_ContextPop, 0, 0);
         sqlite3VdbeAddOp(v, OP_Goto, 0, pParse->trigStack->ignoreJump);
         VdbeComment((v, "# raise(IGNORE)"));
      }
    }
#endif
    break;
  }
}

#ifndef SQLITE_OMIT_TRIGGER
/*
** Generate code that evalutes the given expression and leaves the result
** on the stack.  See also sqlite3ExprCode().
**
** This routine might also cache the result and modify the pExpr tree
** so that it will make use of the cached result on subsequent evaluations
** rather than evaluate the whole expression again.  Trivial expressions are
** not cached.  If the expression is cached, its result is stored in a 
** memory location.
*/
void sqlite3ExprCodeAndCache(Parse *pParse, Expr *pExpr){
  Vdbe *v = pParse->pVdbe;
  int iMem;
  int addr1, addr2;
  if( v==0 ) return;
  addr1 = sqlite3VdbeCurrentAddr(v);
  sqlite3ExprCode(pParse, pExpr);
  addr2 = sqlite3VdbeCurrentAddr(v);
  if( addr2>addr1+1 || sqlite3VdbeGetOp(v, addr1)->opcode==OP_Function ){
    iMem = pExpr->iTable = pParse->nMem++;
    sqlite3VdbeAddOp(v, OP_MemStore, iMem, 0);
    pExpr->op = TK_REGISTER;
  }
}
#endif

/*
** Generate code that pushes the value of every element of the given
** expression list onto the stack.
**
** Return the number of elements pushed onto the stack.
*/
int sqlite3ExprCodeExprList(
  Parse *pParse,     /* Parsing context */
  ExprList *pList    /* The expression list to be coded */
){
  struct ExprList_item *pItem;
  int i, n;
  Vdbe *v;
  if( pList==0 ) return 0;
  v = sqlite3GetVdbe(pParse);
  n = pList->nExpr;
  for(pItem=pList->a, i=0; i<n; i++, pItem++){
    sqlite3ExprCode(pParse, pItem->pExpr);
  }
  return n;
}

/*
** Generate code for a boolean expression such that a jump is made
** to the label "dest" if the expression is true but execution
** continues straight thru if the expression is false.
**
** If the expression evaluates to NULL (neither true nor false), then
** take the jump if the jumpIfNull flag is true.
**
** This code depends on the fact that certain token values (ex: TK_EQ)
** are the same as opcode values (ex: OP_Eq) that implement the corresponding
** operation.  Special comments in vdbe.c and the mkopcodeh.awk script in
** the make process cause these values to align.  Assert()s in the code
** below verify that the numbers are aligned correctly.
*/
void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
  Vdbe *v = pParse->pVdbe;
  int op = 0;
  if( v==0 || pExpr==0 ) return;
  op = pExpr->op;
  switch( op ){
    case TK_AND: {
      int d2 = sqlite3VdbeMakeLabel(v);
      sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2, !jumpIfNull);
      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
      sqlite3VdbeResolveLabel(v, d2);
      break;
    }
    case TK_OR: {
      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
      break;
    }
    case TK_NOT: {
      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
      break;
    }
    case TK_LT:
    case TK_LE:
    case TK_GT:
    case TK_GE:
    case TK_NE:
    case TK_EQ: {
      assert( TK_LT==OP_Lt );
      assert( TK_LE==OP_Le );
      assert( TK_GT==OP_Gt );
      assert( TK_GE==OP_Ge );
      assert( TK_EQ==OP_Eq );
      assert( TK_NE==OP_Ne );
      sqlite3ExprCode(pParse, pExpr->pLeft);
      sqlite3ExprCode(pParse, pExpr->pRight);
      codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op, dest, jumpIfNull);
      break;
    }
    case TK_ISNULL:
    case TK_NOTNULL: {
      assert( TK_ISNULL==OP_IsNull );
      assert( TK_NOTNULL==OP_NotNull );
      sqlite3ExprCode(pParse, pExpr->pLeft);
      sqlite3VdbeAddOp(v, op, 1, dest);
      break;
    }
    case TK_BETWEEN: {
      /* The expression "x BETWEEN y AND z" is implemented as:
      **
      ** 1 IF (x < y) GOTO 3
      ** 2 IF (x <= z) GOTO <dest>
      ** 3 ...
      */
      int addr;
      Expr *pLeft = pExpr->pLeft;
      Expr *pRight = pExpr->pList->a[0].pExpr;
      sqlite3ExprCode(pParse, pLeft);
      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
      sqlite3ExprCode(pParse, pRight);
      addr = codeCompare(pParse, pLeft, pRight, OP_Lt, 0, !jumpIfNull);

      pRight = pExpr->pList->a[1].pExpr;
      sqlite3ExprCode(pParse, pRight);
      codeCompare(pParse, pLeft, pRight, OP_Le, dest, jumpIfNull);

      sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
      sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v));
      sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
      break;
    }
    default: {
      sqlite3ExprCode(pParse, pExpr);
      sqlite3VdbeAddOp(v, OP_If, jumpIfNull, dest);
      break;
    }
  }
}

/*
** Generate code for a boolean expression such that a jump is made
** to the label "dest" if the expression is false but execution
** continues straight thru if the expression is true.
**
** If the expression evaluates to NULL (neither true nor false) then
** jump if jumpIfNull is true or fall through if jumpIfNull is false.
*/
void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
  Vdbe *v = pParse->pVdbe;
  int op = 0;
  if( v==0 || pExpr==0 ) return;

  /* The value of pExpr->op and op are related as follows:
  **
  **       pExpr->op            op
  **       ---------          ----------
  **       TK_ISNULL          OP_NotNull
  **       TK_NOTNULL         OP_IsNull
  **       TK_NE              OP_Eq
  **       TK_EQ              OP_Ne
  **       TK_GT              OP_Le
  **       TK_LE              OP_Gt
  **       TK_GE              OP_Lt
  **       TK_LT              OP_Ge
  **
  ** For other values of pExpr->op, op is undefined and unused.
  ** The value of TK_ and OP_ constants are arranged such that we
  ** can compute the mapping above using the following expression.
  ** Assert()s verify that the computation is correct.
  */
  op = ((pExpr->op+(TK_ISNULL&1))^1)-(TK_ISNULL&1);

  /* Verify correct alignment of TK_ and OP_ constants
  */
  assert( pExpr->op!=TK_ISNULL || op==OP_NotNull );
  assert( pExpr->op!=TK_NOTNULL || op==OP_IsNull );
  assert( pExpr->op!=TK_NE || op==OP_Eq );
  assert( pExpr->op!=TK_EQ || op==OP_Ne );
  assert( pExpr->op!=TK_LT || op==OP_Ge );
  assert( pExpr->op!=TK_LE || op==OP_Gt );
  assert( pExpr->op!=TK_GT || op==OP_Le );
  assert( pExpr->op!=TK_GE || op==OP_Lt );

  switch( pExpr->op ){
    case TK_AND: {
      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
      break;
    }
    case TK_OR: {
      int d2 = sqlite3VdbeMakeLabel(v);
      sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, !jumpIfNull);
      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
      sqlite3VdbeResolveLabel(v, d2);
      break;
    }
    case TK_NOT: {
      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
      break;
    }
    case TK_LT:
    case TK_LE:
    case TK_GT:
    case TK_GE:
    case TK_NE:
    case TK_EQ: {
      sqlite3ExprCode(pParse, pExpr->pLeft);
      sqlite3ExprCode(pParse, pExpr->pRight);
      codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op, dest, jumpIfNull);
      break;
    }
    case TK_ISNULL:
    case TK_NOTNULL: {
      sqlite3ExprCode(pParse, pExpr->pLeft);
      sqlite3VdbeAddOp(v, op, 1, dest);
      break;
    }
    case TK_BETWEEN: {
      /* The expression is "x BETWEEN y AND z". It is implemented as:
      **
      ** 1 IF (x >= y) GOTO 3
      ** 2 GOTO <dest>
      ** 3 IF (x > z) GOTO <dest>
      */
      int addr;
      Expr *pLeft = pExpr->pLeft;
      Expr *pRight = pExpr->pList->a[0].pExpr;
      sqlite3ExprCode(pParse, pLeft);
      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
      sqlite3ExprCode(pParse, pRight);
      addr = sqlite3VdbeCurrentAddr(v);
      codeCompare(pParse, pLeft, pRight, OP_Ge, addr+3, !jumpIfNull);

      sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
      sqlite3VdbeAddOp(v, OP_Goto, 0, dest);
      pRight = pExpr->pList->a[1].pExpr;
      sqlite3ExprCode(pParse, pRight);
      codeCompare(pParse, pLeft, pRight, OP_Gt, dest, jumpIfNull);
      break;
    }
    default: {
      sqlite3ExprCode(pParse, pExpr);
      sqlite3VdbeAddOp(v, OP_IfNot, jumpIfNull, dest);
      break;
    }
  }
}

/*
** Do a deep comparison of two expression trees.  Return TRUE (non-zero)
** if they are identical and return FALSE if they differ in any way.
*/
int sqlite3ExprCompare(Expr *pA, Expr *pB){
  int i;
  if( pA==0 ){
    return pB==0;
  }else if( pB==0 ){
    return 0;
  }
  if( pA->op!=pB->op ) return 0;
  if( !sqlite3ExprCompare(pA->pLeft, pB->pLeft) ) return 0;
  if( !sqlite3ExprCompare(pA->pRight, pB->pRight) ) return 0;
  if( pA->pList ){
    if( pB->pList==0 ) return 0;
    if( pA->pList->nExpr!=pB->pList->nExpr ) return 0;
    for(i=0; i<pA->pList->nExpr; i++){
      if( !sqlite3ExprCompare(pA->pList->a[i].pExpr, pB->pList->a[i].pExpr) ){
        return 0;
      }
    }
  }else if( pB->pList ){
    return 0;
  }
  if( pA->pSelect || pB->pSelect ) return 0;
  if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 0;
  if( pA->token.z ){
    if( pB->token.z==0 ) return 0;
    if( pB->token.n!=pA->token.n ) return 0;
    if( sqlite3StrNICmp(pA->token.z, pB->token.z, pB->token.n)!=0 ) return 0;
  }
  return 1;
}

/*
** Add a new element to the pParse->aAgg[] array and return its index.
** The new element is initialized to zero.  The calling function is
** expected to fill it in.
*/
static int appendAggInfo(Parse *pParse){
  if( (pParse->nAgg & 0x7)==0 ){
    int amt = pParse->nAgg + 8;
    AggExpr *aAgg = sqliteRealloc(pParse->aAgg, amt*sizeof(pParse->aAgg[0]));
    if( aAgg==0 ){
      return -1;
    }
    pParse->aAgg = aAgg;
  }
  memset(&pParse->aAgg[pParse->nAgg], 0, sizeof(pParse->aAgg[0]));
  return pParse->nAgg++;
}

/*
** This is an xFunc for walkExprTree() used to implement 
** sqlite3ExprAnalyzeAggregates().  See sqlite3ExprAnalyzeAggregates
** for additional information.
**
** This routine analyzes the aggregate function at pExpr.
*/
static int analyzeAggregate(void *pArg, Expr *pExpr){
  int i;
  AggExpr *aAgg;
  NameContext *pNC = (NameContext *)pArg;
  Parse *pParse = pNC->pParse;
  SrcList *pSrcList = pNC->pSrcList;

  switch( pExpr->op ){
    case TK_COLUMN: {
      for(i=0; pSrcList && i<pSrcList->nSrc; i++){
        if( pExpr->iTable==pSrcList->a[i].iCursor ){
          aAgg = pParse->aAgg;
          for(i=0; i<pParse->nAgg; i++){
            if( aAgg[i].isAgg ) continue;
            if( aAgg[i].pExpr->iTable==pExpr->iTable
             && aAgg[i].pExpr->iColumn==pExpr->iColumn ){
              break;
            }
          }
          if( i>=pParse->nAgg ){
            i = appendAggInfo(pParse);
            if( i<0 ) return 1;
            pParse->aAgg[i].isAgg = 0;
            pParse->aAgg[i].pExpr = pExpr;
          }
          pExpr->iAgg = i;
          pExpr->iAggCtx = pNC->nDepth;
          return 1;
        }
      }
      return 1;
    }
    case TK_AGG_FUNCTION: {
      if( pNC->nDepth==0 ){
        aAgg = pParse->aAgg;
        for(i=0; i<pParse->nAgg; i++){
          if( !aAgg[i].isAgg ) continue;
          if( sqlite3ExprCompare(aAgg[i].pExpr, pExpr) ){
            break;
          }
        }
        if( i>=pParse->nAgg ){
          u8 enc = pParse->db->enc;
          i = appendAggInfo(pParse);
          if( i<0 ) return 1;
          pParse->aAgg[i].isAgg = 1;
          pParse->aAgg[i].pExpr = pExpr;
          pParse->aAgg[i].pFunc = sqlite3FindFunction(pParse->db,
               pExpr->token.z, pExpr->token.n,
               pExpr->pList ? pExpr->pList->nExpr : 0, enc, 0);
        }
        pExpr->iAgg = i;
        return 1;
      }
    }
  }
  if( pExpr->pSelect ){
    pNC->nDepth++;
    walkSelectExpr(pExpr->pSelect, analyzeAggregate, pNC);
    pNC->nDepth--;
  }
  return 0;
}

/*
** Analyze the given expression looking for aggregate functions and
** for variables that need to be added to the pParse->aAgg[] array.
** Make additional entries to the pParse->aAgg[] array as necessary.
**
** This routine should only be called after the expression has been
** analyzed by sqlite3ExprResolveNames().
**