expr.c

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
*/
#include "sqliteInt.h"

/* Forward declarations */
static void exprCodeBetween(Parse*,Expr*,int,void(*)(Parse*,Expr*,int,int),int);
static int exprCodeVector(Parse *pParse, Expr *p, int *piToFree);

/*
** Return the affinity character for a single column of a table.
*/
char sqlite3TableColumnAffinity(const Table *pTab, int iCol){
  if( iCol<0 || NEVER(iCol>=pTab->nCol) ) return SQLITE_AFF_INTEGER;
  return pTab->aCol[iCol].affinity;
}

/*
** Return the 'affinity' of the expression pExpr if any.
**
** If pExpr is a column, a reference to a column via an 'AS' alias,
** or a sub-select with a column as the return value, then the
** affinity of that column is returned. Otherwise, 0x00 is returned,
** indicating no affinity for the expression.
**
** i.e. the WHERE clause expressions in the following statements all
** have an affinity:
**
** CREATE TABLE t1(a);
** SELECT * FROM t1 WHERE a;
** SELECT a AS b FROM t1 WHERE b;
** SELECT * FROM t1 WHERE (select a from t1);
*/
char sqlite3ExprAffinity(const Expr *pExpr){
  int op;
  op = pExpr->op;
  while( 1 /* exit-by-break */ ){
    if( op==TK_COLUMN || (op==TK_AGG_COLUMN && pExpr->y.pTab!=0) ){
      assert( ExprUseYTab(pExpr) );
      assert( pExpr->y.pTab!=0 );
      return sqlite3TableColumnAffinity(pExpr->y.pTab, pExpr->iColumn);
    }
    if( op==TK_SELECT ){
      assert( ExprUseXSelect(pExpr) );
      assert( pExpr->x.pSelect!=0 );
      assert( pExpr->x.pSelect->pEList!=0 );
      assert( pExpr->x.pSelect->pEList->a[0].pExpr!=0 );
      return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);
    }
#ifndef SQLITE_OMIT_CAST
    if( op==TK_CAST ){
      assert( !ExprHasProperty(pExpr, EP_IntValue) );
      return sqlite3AffinityType(pExpr->u.zToken, 0);
    }
#endif
    if( op==TK_SELECT_COLUMN ){
      assert( pExpr->pLeft!=0 && ExprUseXSelect(pExpr->pLeft) );
      assert( pExpr->iColumn < pExpr->iTable );
      assert( pExpr->iColumn >= 0 );
      assert( pExpr->iTable==pExpr->pLeft->x.pSelect->pEList->nExpr );
      return sqlite3ExprAffinity(
          pExpr->pLeft->x.pSelect->pEList->a[pExpr->iColumn].pExpr
      );
    }
    if( op==TK_VECTOR
     || (op==TK_FUNCTION && pExpr->affExpr==SQLITE_AFF_DEFER)
    ){
      assert( ExprUseXList(pExpr) );
      return sqlite3ExprAffinity(pExpr->x.pList->a[0].pExpr);
    }
    if( ExprHasProperty(pExpr, EP_Skip|EP_IfNullRow) ){
      assert( pExpr->op==TK_COLLATE
           || pExpr->op==TK_IF_NULL_ROW
           || (pExpr->op==TK_REGISTER && pExpr->op2==TK_IF_NULL_ROW) );
      pExpr = pExpr->pLeft;
      op = pExpr->op;
      continue;
    }
    if( op!=TK_REGISTER ) break;
    op = pExpr->op2;
    if( NEVER( op==TK_REGISTER ) ) break;
  }
  return pExpr->affExpr;
}

/*
** Make a guess at all the possible datatypes of the result that could
** be returned by an expression.  Return a bitmask indicating the answer:
**
**     0x01         Numeric
**     0x02         Text
**     0x04         Blob
**
** If the expression must return NULL, then 0x00 is returned.
*/
int sqlite3ExprDataType(const Expr *pExpr){
  while( pExpr ){
    switch( pExpr->op ){
      case TK_COLLATE:
      case TK_IF_NULL_ROW:
      case TK_UPLUS:  {
        pExpr = pExpr->pLeft;
        break;
      }
      case TK_NULL: {
        pExpr = 0;
        break;
      }
      case TK_STRING: {
        return 0x02;
      }
      case TK_BLOB: {
        return 0x04;
      }
      case TK_CONCAT: {
        return 0x06;
      }
      case TK_VARIABLE:
      case TK_AGG_FUNCTION:
      case TK_FUNCTION: {
        return 0x07;
      }
      case TK_COLUMN:
      case TK_AGG_COLUMN:
      case TK_SELECT:
      case TK_CAST:
      case TK_SELECT_COLUMN:
      case TK_VECTOR:  {
        int aff = sqlite3ExprAffinity(pExpr);
        if( aff>=SQLITE_AFF_NUMERIC ) return 0x05;
        if( aff==SQLITE_AFF_TEXT )    return 0x06;
        return 0x07;
      }
      case TK_CASE: {
        int res = 0;
        int ii;
        ExprList *pList = pExpr->x.pList;
        assert( ExprUseXList(pExpr) && pList!=0 );
        assert( pList->nExpr > 0);
        for(ii=1; ii<pList->nExpr; ii+=2){
          res |= sqlite3ExprDataType(pList->a[ii].pExpr);
        }
        if( pList->nExpr % 2 ){
          res |= sqlite3ExprDataType(pList->a[pList->nExpr-1].pExpr);
        }
        return res;
      }
      default: {
        return 0x01;
      }
    } /* End of switch(op) */
  } /* End of while(pExpr) */
  return 0x00;
}

/*
** Set the collating sequence for expression pExpr to be the collating
** sequence named by pToken.   Return a pointer to a new Expr node that
** implements the COLLATE operator.
**
** If a memory allocation error occurs, that fact is recorded in pParse->db
** and the pExpr parameter is returned unchanged.
*/
Expr *sqlite3ExprAddCollateToken(
  const Parse *pParse,     /* Parsing context */
  Expr *pExpr,             /* Add the "COLLATE" clause to this expression */
  const Token *pCollName,  /* Name of collating sequence */
  int dequote              /* True to dequote pCollName */
){
  if( pCollName->n>0 ){
    Expr *pNew = sqlite3ExprAlloc(pParse->db, TK_COLLATE, pCollName, dequote);
    if( pNew ){
      pNew->pLeft = pExpr;
      pNew->flags |= EP_Collate|EP_Skip;
      pExpr = pNew;
    }
  }
  return pExpr;
}
Expr *sqlite3ExprAddCollateString(
  const Parse *pParse,  /* Parsing context */
  Expr *pExpr,          /* Add the "COLLATE" clause to this expression */
  const char *zC        /* The collating sequence name */
){
  Token s;
  assert( zC!=0 );
  sqlite3TokenInit(&s, (char*)zC);
  return sqlite3ExprAddCollateToken(pParse, pExpr, &s, 0);
}

/*
** Skip over any TK_COLLATE operators.
*/
Expr *sqlite3ExprSkipCollate(Expr *pExpr){
  while( pExpr && ExprHasProperty(pExpr, EP_Skip) ){
    assert( pExpr->op==TK_COLLATE );
    pExpr = pExpr->pLeft;
  }  
  return pExpr;
}

/*
** Skip over any TK_COLLATE operators and/or any unlikely()
** or likelihood() or likely() functions at the root of an
** expression.
*/
Expr *sqlite3ExprSkipCollateAndLikely(Expr *pExpr){
  while( pExpr && ExprHasProperty(pExpr, EP_Skip|EP_Unlikely) ){
    if( ExprHasProperty(pExpr, EP_Unlikely) ){
      assert( ExprUseXList(pExpr) );
      assert( pExpr->x.pList->nExpr>0 );
      assert( pExpr->op==TK_FUNCTION );
      pExpr = pExpr->x.pList->a[0].pExpr;
    }else if( pExpr->op==TK_COLLATE ){
      pExpr = pExpr->pLeft;
    }else{
      break;
    }
  }  
  return pExpr;
}

/*
** Return the collation sequence for the expression pExpr. If
** there is no defined collating sequence, return NULL.
**
** See also: sqlite3ExprNNCollSeq()
**
** The sqlite3ExprNNCollSeq() works the same exact that it returns the
** default collation if pExpr has no defined collation.
**
** The collating sequence might be determined by a COLLATE operator
** or by the presence of a column with a defined collating sequence.
** COLLATE operators take first precedence.  Left operands take
** precedence over right operands.
*/
CollSeq *sqlite3ExprCollSeq(Parse *pParse, const Expr *pExpr){
  sqlite3 *db = pParse->db;
  CollSeq *pColl = 0;
  const Expr *p = pExpr;
  while( p ){
    int op = p->op;
    if( op==TK_REGISTER ) op = p->op2;
    if( (op==TK_AGG_COLUMN && p->y.pTab!=0)
     || op==TK_COLUMN || op==TK_TRIGGER
    ){
      int j;
      assert( ExprUseYTab(p) );
      assert( p->y.pTab!=0 );
      if( (j = p->iColumn)>=0 ){
        const char *zColl = sqlite3ColumnColl(&p->y.pTab->aCol[j]);
        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
      }
      break;
    }
    if( op==TK_CAST || op==TK_UPLUS ){
      p = p->pLeft;
      continue;
    }
    if( op==TK_VECTOR
     || (op==TK_FUNCTION && p->affExpr==SQLITE_AFF_DEFER)
    ){
      assert( ExprUseXList(p) );
      p = p->x.pList->a[0].pExpr;
      continue;
    }
    if( op==TK_COLLATE ){
      assert( !ExprHasProperty(p, EP_IntValue) );
      pColl = sqlite3GetCollSeq(pParse, ENC(db), 0, p->u.zToken);
      break;
    }
    if( p->flags & EP_Collate ){
      if( p->pLeft && (p->pLeft->flags & EP_Collate)!=0 ){
        p = p->pLeft;
      }else{
        Expr *pNext  = p->pRight;
        /* The Expr.x union is never used at the same time as Expr.pRight */
        assert( !ExprUseXList(p) || p->x.pList==0 || p->pRight==0 );
        if( ExprUseXList(p) && p->x.pList!=0 && !db->mallocFailed ){
          int i;
          for(i=0; i<p->x.pList->nExpr; i++){
            if( ExprHasProperty(p->x.pList->a[i].pExpr, EP_Collate) ){
              pNext = p->x.pList->a[i].pExpr;
              break;
            }
          }
        }
        p = pNext;
      }
    }else{
      break;
    }
  }
  if( sqlite3CheckCollSeq(pParse, pColl) ){
    pColl = 0;
  }
  return pColl;
}

/*
** Return the collation sequence for the expression pExpr. If
** there is no defined collating sequence, return a pointer to the
** default collation sequence.
**
** See also: sqlite3ExprCollSeq()
**
** The sqlite3ExprCollSeq() routine works the same except that it
** returns NULL if there is no defined collation.
*/
CollSeq *sqlite3ExprNNCollSeq(Parse *pParse, const Expr *pExpr){
  CollSeq *p = sqlite3ExprCollSeq(pParse, pExpr);
  if( p==0 ) p = pParse->db->pDfltColl;
  assert( p!=0 );
  return p;
}

/*
** Return TRUE if the two expressions have equivalent collating sequences.
*/
int sqlite3ExprCollSeqMatch(Parse *pParse, const Expr *pE1, const Expr *pE2){
  CollSeq *pColl1 = sqlite3ExprNNCollSeq(pParse, pE1);
  CollSeq *pColl2 = sqlite3ExprNNCollSeq(pParse, pE2);
  return sqlite3StrICmp(pColl1->zName, pColl2->zName)==0;
}

/*
** pExpr is an operand of a comparison operator.  aff2 is the
** type affinity of the other operand.  This routine returns the
** type affinity that should be used for the comparison operator.
*/
char sqlite3CompareAffinity(const Expr *pExpr, char aff2){
  char aff1 = sqlite3ExprAffinity(pExpr);
  if( aff1>SQLITE_AFF_NONE && aff2>SQLITE_AFF_NONE ){
    /* Both sides of the comparison are columns. If one has numeric
    ** affinity, use that. Otherwise use no affinity.
    */
    if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){
      return SQLITE_AFF_NUMERIC;
    }else{
      return SQLITE_AFF_BLOB;
    }
  }else{
    /* One side is a column, the other is not. Use the columns affinity. */
    assert( aff1<=SQLITE_AFF_NONE || aff2<=SQLITE_AFF_NONE );
    return (aff1<=SQLITE_AFF_NONE ? aff2 : aff1) | SQLITE_AFF_NONE;
  }
}

/*
** pExpr is a comparison operator.  Return the type affinity that should
** be applied to both operands prior to doing the comparison.
*/
static char comparisonAffinity(const Expr *pExpr){
  char aff;
  assert( pExpr->op==TK_EQ || pExpr->op==TK_IN || pExpr->op==TK_LT ||
          pExpr->op==TK_GT || pExpr->op==TK_GE || pExpr->op==TK_LE ||
          pExpr->op==TK_NE || pExpr->op==TK_IS || pExpr->op==TK_ISNOT );
  assert( pExpr->pLeft );
  aff = sqlite3ExprAffinity(pExpr->pLeft);
  if( pExpr->pRight ){
    aff = sqlite3CompareAffinity(pExpr->pRight, aff);
  }else if( ExprUseXSelect(pExpr) ){
    aff = sqlite3CompareAffinity(pExpr->x.pSelect->pEList->a[0].pExpr, aff);
  }else if( aff==0 ){
    aff = SQLITE_AFF_BLOB;
  }
  return aff;
}

/*
** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.
** idx_affinity is the affinity of an indexed column. Return true
** if the index with affinity idx_affinity may be used to implement
** the comparison in pExpr.
*/
int sqlite3IndexAffinityOk(const Expr *pExpr, char idx_affinity){
  char aff = comparisonAffinity(pExpr);
  if( aff<SQLITE_AFF_TEXT ){
    return 1;
  }
  if( aff==SQLITE_AFF_TEXT ){
    return idx_affinity==SQLITE_AFF_TEXT;
  }
  return sqlite3IsNumericAffinity(idx_affinity);
}

/*
** Return the P5 value that should be used for a binary comparison
** opcode (OP_Eq, OP_Ge etc.) used to compare pExpr1 and pExpr2.
*/
static u8 binaryCompareP5(
  const Expr *pExpr1,   /* Left operand */
  const Expr *pExpr2,   /* Right operand */
  int jumpIfNull        /* Extra flags added to P5 */
){
  u8 aff = (char)sqlite3ExprAffinity(pExpr2);
  aff = (u8)sqlite3CompareAffinity(pExpr1, aff) | (u8)jumpIfNull;
  return aff;
}

/*
** Return a pointer to the collation sequence that should be used by
** a binary comparison operator comparing pLeft and pRight.
**
** If the left hand expression has a collating sequence type, then it is
** used. Otherwise the collation sequence for the right hand expression
** is used, or the default (BINARY) if neither expression has a collating
** type.
**
** Argument pRight (but not pLeft) may be a null pointer. In this case,
** it is not considered.
*/
CollSeq *sqlite3BinaryCompareCollSeq(
  Parse *pParse,
  const Expr *pLeft,
  const Expr *pRight
){
  CollSeq *pColl;
  assert( pLeft );
  if( pLeft->flags & EP_Collate ){
    pColl = sqlite3ExprCollSeq(pParse, pLeft);
  }else if( pRight && (pRight->flags & EP_Collate)!=0 ){
    pColl = sqlite3ExprCollSeq(pParse, pRight);
  }else{
    pColl = sqlite3ExprCollSeq(pParse, pLeft);
    if( !pColl ){
      pColl = sqlite3ExprCollSeq(pParse, pRight);
    }
  }
  return pColl;
}

/* Expression p is a comparison operator.  Return a collation sequence
** appropriate for the comparison operator.
**
** This is normally just a wrapper around sqlite3BinaryCompareCollSeq().
** However, if the OP_Commuted flag is set, then the order of the operands
** is reversed in the sqlite3BinaryCompareCollSeq() call so that the
** correct collating sequence is found.
*/
CollSeq *sqlite3ExprCompareCollSeq(Parse *pParse, const Expr *p){
  if( ExprHasProperty(p, EP_Commuted) ){
    return sqlite3BinaryCompareCollSeq(pParse, p->pRight, p->pLeft);
  }else{
    return sqlite3BinaryCompareCollSeq(pParse, p->pLeft, p->pRight);
  }
}

/*
** Generate code for a comparison operator.
*/
static int codeCompare(
  Parse *pParse,    /* The parsing (and code generating) context */
  Expr *pLeft,      /* The left operand */
  Expr *pRight,     /* The right operand */
  int opcode,       /* The comparison opcode */
  int in1, int in2, /* Register holding operands */
  int dest,         /* Jump here if true.  */
  int jumpIfNull,   /* If true, jump if either operand is NULL */
  int isCommuted    /* The comparison has been commuted */
){
  int p5;
  int addr;
  CollSeq *p4;

  if( pParse->nErr ) return 0;
  if( isCommuted ){
    p4 = sqlite3BinaryCompareCollSeq(pParse, pRight, pLeft);
  }else{
    p4 = sqlite3BinaryCompareCollSeq(pParse, pLeft, pRight);
  }
  p5 = binaryCompareP5(pLeft, pRight, jumpIfNull);
  addr = sqlite3VdbeAddOp4(pParse->pVdbe, opcode, in2, dest, in1,
                           (void*)p4, P4_COLLSEQ);
  sqlite3VdbeChangeP5(pParse->pVdbe, (u16)p5);
  return addr;
}

/*
** Return true if expression pExpr is a vector, or false otherwise.
**
** A vector is defined as any expression that results in two or more
** columns of result.  Every TK_VECTOR node is an vector because the
** parser will not generate a TK_VECTOR with fewer than two entries.
** But a TK_SELECT might be either a vector or a scalar. It is only
** considered a vector if it has two or more result columns.
*/
int sqlite3ExprIsVector(const Expr *pExpr){
  return sqlite3ExprVectorSize(pExpr)>1;
}

/*
** If the expression passed as the only argument is of type TK_VECTOR
** return the number of expressions in the vector. Or, if the expression
** is a sub-select, return the number of columns in the sub-select. For
** any other type of expression, return 1.
*/
int sqlite3ExprVectorSize(const Expr *pExpr){
  u8 op = pExpr->op;
  if( op==TK_REGISTER ) op = pExpr->op2;
  if( op==TK_VECTOR ){
    assert( ExprUseXList(pExpr) );
    return pExpr->x.pList->nExpr;
  }else if( op==TK_SELECT ){
    assert( ExprUseXSelect(pExpr) );
    return pExpr->x.pSelect->pEList->nExpr;
  }else{
    return 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.
**
** If pVector is really a scalar (and "scalar" here includes subqueries
** that return a single column!) then return pVector unmodified.
**
** 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 may
** not be ready for evaluation because the table cursor has not yet
** been positioned.
*/
Expr *sqlite3VectorFieldSubexpr(Expr *pVector, int i){
  assert( i<sqlite3ExprVectorSize(pVector) || pVector->op==TK_ERROR );
  if( sqlite3ExprIsVector(pVector) ){
    assert( pVector->op2==0 || pVector->op==TK_REGISTER );
    if( pVector->op==TK_SELECT || pVector->op2==TK_SELECT ){
      assert( ExprUseXSelect(pVector) );
      return pVector->x.pSelect->pEList->a[i].pExpr;
    }else{
      assert( ExprUseXList(pVector) );
      return pVector->x.pList->a[i].pExpr;
    }
  }
  return pVector;
}

/*
** 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.
**
** It is ok for pVector to be a scalar (as long as iField==0). 
** In that case, this routine works like sqlite3ExprDup().
**
** The caller owns the returned Expr object and is responsible for
** ensuring that the returned value eventually gets freed.
**
** The caller retains ownership of pVector.  If pVector is a TK_SELECT,
** then the returned object will reference pVector and so pVector must remain
** valid for the life of the returned object.  If pVector is a TK_VECTOR
** or a scalar expression, then it can be deleted as soon as this routine
** returns.
**
** A trick to cause a TK_SELECT pVector to be deleted together with
** the returned Expr object is to attach the pVector to the pRight field
** of the returned TK_SELECT_COLUMN Expr object.
*/
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 nField           /* Total number of columns in the vector */
){
  Expr *pRet;
  if( pVector->op==TK_SELECT ){
    assert( ExprUseXSelect(pVector) );
    /* The TK_SELECT_COLUMN Expr node:
    **
    ** pLeft:           pVector containing TK_SELECT.  Not deleted.
    ** pRight:          not used.  But recursively deleted.
    ** iColumn:         Index of a column in pVector
    ** iTable:          0 or the number of columns on the LHS of an assignment
    ** 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
    ** can be attached to pRight to cause this node to take ownership of
    ** pVector.  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, 0, 0);
    if( pRet ){
      ExprSetProperty(pRet, EP_FullSize);
      pRet->iTable = nField;
      pRet->iColumn = iField;
      pRet->pLeft = pVector;
    }
  }else{
    if( pVector->op==TK_VECTOR ){
      Expr **ppVector;
      assert( ExprUseXList(pVector) );
      ppVector = &pVector->x.pList->a[iField].pExpr;
      pVector = *ppVector;
      if( IN_RENAME_OBJECT ){
        /* This must be a vector UPDATE inside a trigger */
        *ppVector = 0;
        return pVector;
      }
    }
    pRet = sqlite3ExprDup(pParse->db, pVector, 0);
  }
  return pRet;
}

/*
** 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).
**
** If pExpr is not a TK_SELECT expression, return 0.
*/
static int exprCodeSubselect(Parse *pParse, Expr *pExpr){
  int reg = 0;
#ifndef SQLITE_OMIT_SUBQUERY
  if( pExpr->op==TK_SELECT ){
    reg = sqlite3CodeSubselect(pParse, pExpr);
  }
#endif
  return reg;
}

/*
** Argument pVector points to a vector expression - either a TK_VECTOR
** or TK_SELECT that returns more than one column. This function returns
** the register number of a register that contains the value of
** element iField of the vector.
**
** If pVector is a TK_SELECT expression, then code for it must have
** already been generated using the exprCodeSubselect() routine. In this
** case parameter regSelect should be the first in an array of registers
** containing the results of the sub-select.
**
** If pVector is of type TK_VECTOR, then code for the requested field
** is generated. In this case (*pRegFree) may be set to the number of
** a temporary register to be freed by the caller before returning.
**
** Before returning, output parameter (*ppExpr) is set to point to the
** Expr object corresponding to element iElem of the vector.
*/
static int exprVectorRegister(
  Parse *pParse,                  /* Parse context */
  Expr *pVector,                  /* Vector to extract element from */
  int iField,                     /* Field to extract from pVector */
  int regSelect,                  /* First in array of registers */
  Expr **ppExpr,                  /* OUT: Expression element */
  int *pRegFree                   /* OUT: Temp register to free */
){
  u8 op = pVector->op;
  assert( op==TK_VECTOR || op==TK_REGISTER || op==TK_SELECT || op==TK_ERROR );
  if( op==TK_REGISTER ){
    *ppExpr = sqlite3VectorFieldSubexpr(pVector, iField);
    return pVector->iTable+iField;
  }
  if( op==TK_SELECT ){
    assert( ExprUseXSelect(pVector) );
    *ppExpr = pVector->x.pSelect->pEList->a[iField].pExpr;
     return regSelect+iField;
  }
  if( op==TK_VECTOR ){
    assert( ExprUseXList(pVector) );
    *ppExpr = pVector->x.pList->a[iField].pExpr;
    return sqlite3ExprCodeTemp(pParse, *ppExpr, pRegFree);
  }
  return 0;
}

/*
** Expression pExpr is a comparison between two vector values. Compute
** the result of the comparison (1, 0, or NULL) and write that
** result into register dest.
**
** The caller must satisfy the following preconditions:
**
**    if pExpr->op==TK_IS:      op==TK_EQ and p5==SQLITE_NULLEQ
**    if pExpr->op==TK_ISNOT:   op==TK_NE and p5==SQLITE_NULLEQ
**    otherwise:                op==pExpr->op and p5==0
*/
static void codeVectorCompare(
  Parse *pParse,        /* Code generator context */
  Expr *pExpr,          /* The comparison operation */
  int dest,             /* Write results into this register */
  u8 op,                /* Comparison operator */
  u8 p5                 /* SQLITE_NULLEQ or zero */
){
  Vdbe *v = pParse->pVdbe;
  Expr *pLeft = pExpr->pLeft;
  Expr *pRight = pExpr->pRight;
  int nLeft = sqlite3ExprVectorSize(pLeft);
  int i;
  int regLeft = 0;
  int regRight = 0;
  u8 opx = op;
  int addrCmp = 0;
  int addrDone = sqlite3VdbeMakeLabel(pParse);
  int isCommuted = ExprHasProperty(pExpr,EP_Commuted);

  assert( !ExprHasVVAProperty(pExpr,EP_Immutable) );
  if( pParse->nErr ) return;
  if( nLeft!=sqlite3ExprVectorSize(pRight) ){
    sqlite3ErrorMsg(pParse, "row value misused");
    return;
  }
  assert( pExpr->op==TK_EQ || pExpr->op==TK_NE
       || pExpr->op==TK_IS || pExpr->op==TK_ISNOT
       || pExpr->op==TK_LT || pExpr->op==TK_GT
       || pExpr->op==TK_LE || pExpr->op==TK_GE
  );
  assert( pExpr->op==op || (pExpr->op==TK_IS && op==TK_EQ)
            || (pExpr->op==TK_ISNOT && op==TK_NE) );
  assert( p5==0 || pExpr->op!=op );
  assert( p5==SQLITE_NULLEQ || pExpr->op==op );

  if( op==TK_LE ) opx = TK_LT;
  if( op==TK_GE ) opx = TK_GT;
  if( op==TK_NE ) opx = TK_EQ;

  regLeft = exprCodeSubselect(pParse, pLeft);
  regRight = exprCodeSubselect(pParse, pRight);

  sqlite3VdbeAddOp2(v, OP_Integer, 1, dest);
  for(i=0; 1 /*Loop exits by "break"*/; i++){
    int regFree1 = 0, regFree2 = 0;
    Expr *pL = 0, *pR = 0;
    int r1, r2;
    assert( i>=0 && i<nLeft );
    if( addrCmp ) sqlite3VdbeJumpHere(v, addrCmp);
    r1 = exprVectorRegister(pParse, pLeft, i, regLeft, &pL, &regFree1);
    r2 = exprVectorRegister(pParse, pRight, i, regRight, &pR, &regFree2);
    addrCmp = sqlite3VdbeCurrentAddr(v);
    codeCompare(pParse, pL, pR, opx, r1, r2, addrDone, p5, isCommuted);
    testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
    testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
    testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
    testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
    testcase(op==OP_Eq); VdbeCoverageIf(v,op==OP_Eq);
    testcase(op==OP_Ne); VdbeCoverageIf(v,op==OP_Ne);
    sqlite3ReleaseTempReg(pParse, regFree1);
    sqlite3ReleaseTempReg(pParse, regFree2);
    if( (opx==TK_LT || opx==TK_GT) && i<nLeft-1 ){
      addrCmp = sqlite3VdbeAddOp0(v, OP_ElseEq);
      testcase(opx==TK_LT); VdbeCoverageIf(v,opx==TK_LT);
      testcase(opx==TK_GT); VdbeCoverageIf(v,opx==TK_GT);
    }
    if( p5==SQLITE_NULLEQ ){
      sqlite3VdbeAddOp2(v, OP_Integer, 0, dest);
    }else{
      sqlite3VdbeAddOp3(v, OP_ZeroOrNull, r1, dest, r2);
    }
    if( i==nLeft-1 ){
      break;
    }
    if( opx==TK_EQ ){
      sqlite3VdbeAddOp2(v, OP_NotNull, dest, addrDone); VdbeCoverage(v);
    }else{
      assert( op==TK_LT || op==TK_GT || op==TK_LE || op==TK_GE );
      sqlite3VdbeAddOp2(v, OP_Goto, 0, addrDone);
      if( i==nLeft-2 ) opx = op;
    }
  }
  sqlite3VdbeJumpHere(v, addrCmp);
  sqlite3VdbeResolveLabel(v, addrDone);
  if( op==TK_NE ){
    sqlite3VdbeAddOp2(v, OP_Not, dest, dest);
  }
}

#if SQLITE_MAX_EXPR_DEPTH>0
/*
** Check that argument nHeight is less than or equal to the maximum
** expression depth allowed. If it is not, leave an error message in
** pParse.
*/
int sqlite3ExprCheckHeight(Parse *pParse, int nHeight){
  int rc = SQLITE_OK;
  int mxHeight = pParse->db->aLimit[SQLITE_LIMIT_EXPR_DEPTH];
  if( nHeight>mxHeight ){
    sqlite3ErrorMsg(pParse,
       "Expression tree is too large (maximum depth %d)", mxHeight
    );
    rc = SQLITE_ERROR;
  }
  return rc;
}

/* The following three functions, heightOfExpr(), heightOfExprList()
** and heightOfSelect(), are used to determine the maximum height
** of any expression tree referenced by the structure passed as the
** first argument.
**
** If this maximum height is greater than the current value pointed
** to by pnHeight, the second parameter, then set *pnHeight to that
** value.
*/
static void heightOfExpr(const Expr *p, int *pnHeight){
  if( p ){
    if( p->nHeight>*pnHeight ){
      *pnHeight = p->nHeight;
    }
  }
}
static void heightOfExprList(const ExprList *p, int *pnHeight){
  if( p ){
    int i;
    for(i=0; i<p->nExpr; i++){
      heightOfExpr(p->a[i].pExpr, pnHeight);
    }
  }
}
static void heightOfSelect(const Select *pSelect, int *pnHeight){
  const Select *p;
  for(p=pSelect; p; p=p->pPrior){
    heightOfExpr(p->pWhere, pnHeight);
    heightOfExpr(p->pHaving, pnHeight);
    heightOfExpr(p->pLimit, pnHeight);
    heightOfExprList(p->pEList, pnHeight);
    heightOfExprList(p->pGroupBy, pnHeight);
    heightOfExprList(p->pOrderBy, pnHeight);
  }
}

/*
** Set the Expr.nHeight variable in the structure passed as an
** argument. An expression with no children, Expr.pList or
** Expr.pSelect member has a height of 1. Any other expression
** has a height equal to the maximum height of any other
** referenced Expr plus one.
**
** Also propagate EP_Propagate flags up from Expr.x.pList to Expr.flags,
** if appropriate.
*/
static void exprSetHeight(Expr *p){
  int nHeight = p->pLeft ? p->pLeft->nHeight : 0;
  if( NEVER(p->pRight) && p->pRight->nHeight>nHeight ){
    nHeight = p->pRight->nHeight;
  }
  if( ExprUseXSelect(p) ){
    heightOfSelect(p->x.pSelect, &nHeight);
  }else if( p->x.pList ){
    heightOfExprList(p->x.pList, &nHeight);
    p->flags |= EP_Propagate & sqlite3ExprListFlags(p->x.pList);
  }
  p->nHeight = nHeight + 1;
}

/*
** Set the Expr.nHeight variable using the exprSetHeight() function. If
** the height is greater than the maximum allowed expression depth,
** leave an error in pParse.
**
** Also propagate all EP_Propagate flags from the Expr.x.pList into
** Expr.flags.
*/
void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p){
  if( pParse->nErr ) return;
  exprSetHeight(p);
  sqlite3ExprCheckHeight(pParse, p->nHeight);
}

/*
** Return the maximum height of any expression tree referenced
** by the select statement passed as an argument.
*/
int sqlite3SelectExprHeight(const Select *p){
  int nHeight = 0;
  heightOfSelect(p, &nHeight);
  return nHeight;
}
#else /* ABOVE:  Height enforcement enabled.  BELOW: Height enforcement off */
/*
** Propagate all EP_Propagate flags from the Expr.x.pList into
** Expr.flags.
*/
void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p){
  if( pParse->nErr ) return;
  if( p && ExprUseXList(p) && p->x.pList ){
    p->flags |= EP_Propagate & sqlite3ExprListFlags(p->x.pList);
  }
}
#define exprSetHeight(y)
#endif /* SQLITE_MAX_EXPR_DEPTH>0 */

/*
** Set the error offset for an Expr node, if possible.
*/
void sqlite3ExprSetErrorOffset(Expr *pExpr, int iOfst){
  if( pExpr==0 ) return;
  if( NEVER(ExprUseWJoin(pExpr)) ) return;
  pExpr->w.iOfst = iOfst;
}

/*
** This routine is the core allocator for Expr nodes.
**
** Construct a new expression node and return a pointer to it.  Memory
** for this node and for the pToken argument is a single allocation
** obtained from sqlite3DbMalloc().  The calling function
** is responsible for making sure the node eventually gets freed.
**
** If dequote is true, then the token (if it exists) is dequoted.
** If dequote is false, no dequoting is performed.  The deQuote
** parameter is ignored if pToken is NULL or if the token does not
** appear to be quoted.  If the quotes were of the form "..." (double-quotes)
** then the EP_DblQuoted flag is set on the expression node.
**
** Special case (tag-20240227-a):  If op==TK_INTEGER and pToken points to
** a string that can be translated into a 32-bit integer, then the token is
** not stored in u.zToken.  Instead, the integer values is written
** into u.iValue and the EP_IntValue flag is set. No extra storage
** is allocated to hold the integer text and the dequote flag is ignored.
** See also tag-20240227-b.
*/
Expr *sqlite3ExprAlloc(
  sqlite3 *db,            /* Handle for sqlite3DbMallocRawNN() */
  int op,                 /* Expression opcode */
  const Token *pToken,    /* Token argument.  Might be NULL */
  int dequote             /* True to dequote */
){
  Expr *pNew;
  int nExtra = 0;
  int iValue = 0;

  assert( db!=0 );
  if( pToken ){
    if( op!=TK_INTEGER || pToken->z==0
          || sqlite3GetInt32(pToken->z, &iValue)==0 ){
      nExtra = pToken->n+1;  /* tag-20240227-a */
      assert( iValue>=0 );
    }
  }
  pNew = sqlite3DbMallocRawNN(db, sizeof(Expr)+nExtra);
  if( pNew ){
    memset(pNew, 0, sizeof(Expr));
    pNew->op = (u8)op;
    pNew->iAgg = -1;
    if( pToken ){
      if( nExtra==0 ){
        pNew->flags |= EP_IntValue|EP_Leaf|(iValue?EP_IsTrue:EP_IsFalse);
        pNew->u.iValue = iValue;
      }else{
        pNew->u.zToken = (char*)&pNew[1];
        assert( pToken->z!=0 || pToken->n==0 );
        if( pToken->n ) memcpy(pNew->u.zToken, pToken->z, pToken->n);
        pNew->u.zToken[pToken->n] = 0;
        if( dequote && sqlite3Isquote(pNew->u.zToken[0]) ){
          sqlite3DequoteExpr(pNew);
        }
      }
    }
#if SQLITE_MAX_EXPR_DEPTH>0
    pNew->nHeight = 1;
#endif 
  }
  return pNew;
}

/*
** Allocate a new expression node from a zero-terminated token that has
** already been dequoted.
*/
Expr *sqlite3Expr(
  sqlite3 *db,            /* Handle for sqlite3DbMallocZero() (may be null) */
  int op,                 /* Expression opcode */
  const char *zToken      /* Token argument.  Might be NULL */
){
  Token x;
  x.z = zToken;
  x.n = sqlite3Strlen30(zToken);
  return sqlite3ExprAlloc(db, op, &x, 0);
}

/*
** Attach subtrees pLeft and pRight to the Expr node pRoot.
**
** If pRoot==NULL that means that a memory allocation error has occurred.
** In that case, delete the subtrees pLeft and pRight.
*/
void sqlite3ExprAttachSubtrees(
  sqlite3 *db,
  Expr *pRoot,
  Expr *pLeft,
  Expr *pRight