SQLite

    return pExpr->x.pSelect->pEList->nExpr;
  }
  return pExpr->x.pList->nExpr;
}

#ifndef SQLITE_OMIT_SUBQUERY
/*
** Interpret the pVector input as a vector expression.  If pVector is
** an ordinary scalar expression, treat it as a vector of size 1.
**
** Return a pointer to a subexpression of pVector that is the i-th

** column of the vector (numbered starting with 0).  The caller must
** ensure that i is within range.
**
** pVector retains ownership of the returned subexpression.
**
** If the vector is a (SELECT ...) then the expression returned is
** just the expression for the i-th term of the result set, and is
** necessarily ready to be evaluated because the table cursor might
** not have been positioned yet.
*/
Expr *sqlite3VectorFieldSubexpr(Expr *pVector, int i){
  assert( i<sqlite3ExprVectorSize(pVector) );
  if( sqlite3ExprIsVector(pVector) ){
    if( pVector->op==TK_SELECT ){
      return pVector->x.pSelect->pEList->a[i].pExpr;
    }else{
      return pVector->x.pList->a[i].pExpr;
    }
  }
  return pVector;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) */

#ifndef SQLITE_OMIT_SUBQUERY
/*
** Compute and return a new Expr object which when passed to
** sqlite3ExprCode() will generate all necessary code to compute
** the iField-th column of the vector expression pVector.
**
** The caller owns the returned Expr object and is responsible for
** ensuring that the returned value eventually gets freed.
**
** Ownership of pVector is controlled by the takeOwnership parameter.  If
** takeOwnership is true, this routine takes responsibility for freeing
** pVector, and may do so before returning, hence the caller must not reference
** pVector again.  If takeOwnership is false, then the caller takes
** responsibility for freeing pVector and must ensure the pVector remains
** valid as long as the returned value remains in use.
*/
Expr *sqlite3ExprForVectorField(
  Parse *pParse,       /* Parsing context */
  Expr *pVector,       /* The vector.  List of expressions or a sub-SELECT */
  int iField,          /* Which column of the vector to return */
  int takeOwnership    /* True to take ownership of pVector before returning */
){
  Expr *pRet;
  assert( sqlite3ExprIsVector(pVector) );
  /* FIXME: Add support for takeOwnership!=0 */ assert( takeOwnership==0 );
  if( pVector->flags & EP_xIsSelect ){
    /* The TK_SELECT_COLUMN Expr node:
    **
    ** pLeft:           pVector containing TK_SELECT
    ** pRight:          pVector if ownership taken
    ** iColumn:         Index of a column in pVector
    ** pLeft->iTable:   First in an array of register holding result, or 0
    **                  if the result is not yet computed.
    **
    ** sqlite3ExprDelete() specifically skips the recursive delete of
    ** pLeft on TK_SELECT_COLUMN nodes.  But pRight is followed, so pVector
    ** is included on pRight if ownership is taken.  Typically there will
    ** be multiple TK_SELECT_COLUMN nodes with the same pLeft pointer to 
    ** the pVector, but only one of them will own the pVector.
    */
    pRet = sqlite3PExpr(pParse, TK_SELECT_COLUMN, pVector, 0, 0);
    if( pRet ) pRet->iColumn = iField;
    assert( pRet==0 || pRet->iTable==0 );
  }else{
    pRet = sqlite3ExprDup(pParse->db, pVector->x.pList->a[iField].pExpr, 0);
  }
  return pRet;
}
#endif /* !define(SQLITE_OMIT_SUBQUERY) */

/*
** If expression pExpr is of type TK_SELECT, generate code to evaluate
** it. Return the register in which the result is stored (or, if the 
** sub-select returns more than one column, the first in an array
** of registers in which the result is stored).
**

      int affinity_ok = 1;
      int i;

      /* Check that the affinity that will be used to perform each 
      ** comparison is the same as the affinity of each column. If
      ** it not, it is not possible to use any index.  */
      for(i=0; i<nExpr && affinity_ok; i++){
        Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
        int iCol = pEList->a[i].pExpr->iColumn;
        char idxaff = pTab->aCol[iCol].affinity;
        char cmpaff = sqlite3CompareAffinity(pLhs, idxaff);
        switch( cmpaff ){
          case SQLITE_AFF_BLOB:
            break;
          case SQLITE_AFF_TEXT:

      for(pIdx=pTab->pIndex; pIdx && eType==0 && affinity_ok; pIdx=pIdx->pNext){
        if( pIdx->nKeyCol<nExpr ) continue;
        if( mustBeUnique && (pIdx->nKeyCol!=nExpr || !IsUniqueIndex(pIdx)) ){
          continue;
        }

        for(i=0; i<nExpr; i++){
          Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
          Expr *pRhs = pEList->a[i].pExpr;
          CollSeq *pReq = sqlite3BinaryCompareCollSeq(pParse, pLhs, pRhs);
          int j;

          assert( pReq || pParse->nErr );
          if( pReq==0 ) break;

  char *zRet;

  assert( pExpr->op==TK_IN );
  zRet = sqlite3DbMallocZero(pParse->db, nVal+1);
  if( zRet ){
    int i;
    for(i=0; i<nVal; i++){
      Expr *pA = sqlite3VectorFieldSubexpr(pLeft, i);
      char a = sqlite3ExprAffinity(pA);
      if( pSelect ){
        zRet[i] = sqlite3CompareAffinity(pSelect->pEList->a[i].pExpr, a);
      }else{
        zRet[i] = a;
      }
    }

          }
          sqlite3DbFree(pParse->db, dest.zAffSdst);
          assert( pKeyInfo!=0 ); /* OOM will cause exit after sqlite3Select() */
          assert( pEList!=0 );
          assert( pEList->nExpr>0 );
          assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
          for(i=0; i<nVal; i++){
            Expr *p = (nVal>1) ? sqlite3VectorFieldSubexpr(pLeft, i) : pLeft;
            pKeyInfo->aColl[i] = sqlite3BinaryCompareCollSeq(
                pParse, p, pEList->a[i].pExpr
            );
          }
        }
      }else if( ALWAYS(pExpr->x.pList!=0) ){
        /* Case 2:     expr IN (exprlist)

  if( nVector>1 && (pLeft->flags & EP_xIsSelect) ){
    int regSelect = sqlite3CodeSubselect(pParse, pLeft, 0, 0);
    for(i=0; i<nVector; i++){
      sqlite3VdbeAddOp3(v, OP_Copy, regSelect+i, r1+aiMap[i], 0);
    }
  }else{
    for(i=0; i<nVector; i++){
      Expr *pLhs = sqlite3VectorFieldSubexpr(pLeft, i);
      sqlite3ExprCode(pParse, pLhs, r1+aiMap[i]);
    }
  }

  /* If sqlite3FindInIndex() did not find or create an index that is
  ** suitable for evaluating the IN operator, then evaluate using a
  ** sequence of comparisons.

    **
    ** Otherwise, if NULL and false are handled differently, and the
    ** IN(...) operation is not a vector operation, and the LHS of the
    ** operator is NULL, then the result is false if the index is 
    ** completely empty, or NULL otherwise.  */
    if( destIfNull==destIfFalse ){
      for(i=0; i<nVector; i++){
        Expr *p = sqlite3VectorFieldSubexpr(pExpr->pLeft, i);
        if( sqlite3ExprCanBeNull(p) ){
          sqlite3VdbeAddOp2(v, OP_IsNull, r1+aiMap[i], destIfNull);
          VdbeCoverage(v);
        }
      }
    }else if( nVector==1 && sqlite3ExprCanBeNull(pExpr->pLeft) ){
      int addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, r1); VdbeCoverage(v);

        addrNext = 1+sqlite3VdbeAddOp2(v, OP_Rewind, iIdx, destIfFalse);
        VdbeCoverage(v);

        for(i=0; i<nVector; i++){
          Expr *p;
          CollSeq *pColl;
          int r2 = sqlite3GetTempReg(pParse);
          p = sqlite3VectorFieldSubexpr(pLeft, i);
          pColl = sqlite3ExprCollSeq(pParse, p);

          sqlite3VdbeAddOp3(v, OP_Column, iIdx, i, r2);
          sqlite3VdbeAddOp4(v, OP_Eq, r1+i, 0, r2, (void*)pColl,P4_COLLSEQ);
          sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
          VdbeCoverage(v);
          sqlite3VdbeAddOp2(v, OP_Next, iIdx, addrNext);
          VdbeCoverage(v);
          sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);
          sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-3);
          sqlite3ReleaseTempReg(pParse, r2);
        }
        sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfNull);

        /* The key was found in the index. If it contains any NULL values,
        ** then the result of the IN(...) operator is NULL. Otherwise, the
        ** result is 1.  */
        sqlite3VdbeJumpHere(v, addr);
        for(i=0; i<nVector; i++){
          Expr *p = sqlite3VectorFieldSubexpr(pExpr->pLeft, i);
          if( sqlite3ExprCanBeNull(p) ){
            sqlite3VdbeAddOp2(v, OP_IsNull, r1+aiMap[i], destIfNull);
            VdbeCoverage(v);
          }
        }

      }else if( rRhsHasNull==0 ){

      testcase( op==TK_SELECT );
      if( op==TK_SELECT && (nCol = pExpr->x.pSelect->pEList->nExpr)!=1 ){
        sqlite3SubselectError(pParse, nCol, 1);
      }else{
        inReg = sqlite3CodeSubselect(pParse, pExpr, 0, 0);
      }
      break;
    }
    case TK_SELECT_COLUMN: {
      if( pExpr->pLeft->iTable==0 ){
        pExpr->pLeft->iTable = sqlite3CodeSubselect(pParse, pExpr->pLeft, 0, 0);
      }
      inReg = pExpr->pLeft->iTable + pExpr->iColumn;
      break;
    }
    case TK_IN: {
      int destIfFalse = sqlite3VdbeMakeLabel(v);
      int destIfNull = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp2(v, OP_Null, 0, target);
      sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull);
      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);

#if SQLITE_MAX_EXPR_DEPTH>0
  int nHeight;           /* Height of the tree headed by this node */
#endif
  int iTable;            /* TK_COLUMN: cursor number of table holding column
                         ** TK_REGISTER: register number
                         ** TK_TRIGGER: 1 -> new, 0 -> old
                         ** EP_Unlikely:  134217728 times likelihood
                         ** TK_SELECT: 1st register of result vector */
  ynVar iColumn;         /* TK_COLUMN: column index.  -1 for rowid.
                         ** TK_VARIABLE: variable number (always >= 1).
                         ** TK_SELECT_COLUMN: column of the result vector */
  i16 iAgg;              /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
  i16 iRightJoinTable;   /* If EP_FromJoin, the right table of the join */
  u8 op2;                /* TK_REGISTER: original value of Expr.op
                         ** TK_COLUMN: the value of p5 for OP_Column
                         ** TK_AGG_FUNCTION: nesting depth */
  AggInfo *pAggInfo;     /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */
  Table *pTab;           /* Table for TK_COLUMN expressions. */

#if defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)
int sqlite3DbstatRegister(sqlite3*);
#endif

int sqlite3ExprVectorSize(Expr *pExpr);
int sqlite3ExprIsVector(Expr *pExpr);
Expr *sqlite3VectorFieldSubexpr(Expr*, int);
Expr *sqlite3ExprForVectorField(Parse*,Expr*,int,int);

#endif /* SQLITEINT_H */

    alloc.pParse = pParse;
    alloc.pIdx = pIdx;
    alloc.ppRec = ppRec;

    for(i=0; i<nElem; i++){
      sqlite3_value *pVal = 0;
      Expr *pElem = (pExpr ? sqlite3VectorFieldSubexpr(pExpr, i) : 0);
      u8 aff = sqlite3IndexColumnAffinity(pParse->db, pIdx, iVal+i);
      alloc.iVal = iVal+i;
      rc = stat4ValueFromExpr(pParse, pElem, aff, &alloc, &pVal);
      if( !pVal ) break;
      nExtract++;
    }
  }

  Expr *pX = pTerm->pExpr;
  Vdbe *v = pParse->pVdbe;
  int iReg;                  /* Register holding results */

  assert( pLevel->pWLoop->aLTerm[iEq]==pTerm );
  assert( iTarget>0 );
  if( pX->op==TK_EQ || pX->op==TK_IS ){


























    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);

  }else if( pX->op==TK_ISNULL ){
    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{
    int eType;
    int iTab;

      pTerm = pLoop->aLTerm[j];
      if( NEVER(pTerm==0) ) continue;
      if( pTerm->eOperator & WO_IN ){
        codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget);
        addrNotFound = pLevel->addrNxt;
      }else{
        Expr *pRight = pTerm->pExpr->pRight;



        codeExprOrVector(pParse, pRight, iTarget, 1);

      }
    }
    sqlite3VdbeAddOp2(v, OP_Integer, pLoop->u.vtab.idxNum, iReg);
    sqlite3VdbeAddOp2(v, OP_Integer, nConstraint, iReg+1);
    sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrNotFound, iReg,
                      pLoop->u.vtab.idxStr,
                      pLoop->u.vtab.needFree ? P4_MPRINTF : P4_STATIC);

        return 1;
      }
    }
  }
  return 0;
}
























/*
** The input to this routine is an WhereTerm structure with only the
** "pExpr" field filled in.  The job of this routine is to analyze the
** subexpression and populate all the other fields of the WhereTerm
** structure.
**
** If the expression is of the form "<expr> <op> X" it gets commuted

  )){
    int nLeft = sqlite3ExprVectorSize(pExpr->pLeft);
    if( nLeft==sqlite3ExprVectorSize(pExpr->pRight) ){
      int i;
      for(i=0; i<sqlite3ExprVectorSize(pExpr->pLeft); i++){
        int idxNew;
        Expr *pNew;
        Expr *pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i, 0);
        Expr *pRight = sqlite3ExprForVectorField(pParse, pExpr->pRight, i, 0);

        pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight, 0);
        idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
        exprAnalyze(pSrc, pWC, idxNew);
        markTermAsChild(pWC, idxNew, idxTerm);
      }
      pTerm = &pWC->a[idxTerm];
      pTerm->wtFlags = TERM_CODED;
      pTerm->eOperator = 0;
    }
  }

  /* If there is a vector IN term - e.g. "(a, b) IN (SELECT ...)" - create
  ** a virtual term for each vector component. The expression object
  ** used by each such virtual term is pExpr (the full vector IN(...) 
  ** expression). The WhereTerm.iField variable identifies the index within