SQLite

  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;
        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]) ){

  }else{
    assert( pParse->db->mallocFailed );
    sqlite3SelectDelete(pParse->db, pSelect);
  }
}


/*
** If the expression is always either TRUE or FALSE (respectively),
** then return 1.  If one cannot determine the truth value of the
** expression at compile-time return 0.
**
** This is an optimization.  If is OK to return 0 here even if
** the expression really is always false or false (a false negative).
** But it is a bug to return 1 if the expression might have different
** boolean values in different circumstances (a false positive.)
**
** Note that if the expression is part of conditional for a
** LEFT JOIN, then we cannot determine at compile-time whether or not
** is it true or false, so always return 0.
*/
static int exprAlwaysTrue(Expr *p){
  int v = 0;
  if( ExprHasProperty(p, EP_FromJoin) ) return 0;
  if( !sqlite3ExprIsInteger(p, &v) ) return 0;
  return v!=0;
}
static int exprAlwaysFalse(Expr *p){
  int v = 0;
  if( ExprHasProperty(p, EP_FromJoin) ) return 0;
  if( !sqlite3ExprIsInteger(p, &v) ) return 0;
  return v==0;
}

/*
** Join two expressions using an AND operator.  If either expression is
** NULL, then just return the other expression.
**
** If one side or the other of the AND is known to be false, then instead
** of returning an AND expression, just return a constant expression with
** a value of false.
*/
Expr *sqlite3ExprAnd(Parse *pParse, Expr *pLeft, Expr *pRight){
  sqlite3 *db = pParse->db;
  if( pLeft==0  ){
    return pRight;
  }else if( pRight==0 ){
    return pLeft;
  }else if( pParse->nErr || IN_RENAME_OBJECT ){
    return sqlite3PExpr(pParse, TK_AND, pLeft, pRight);
  }else if( exprAlwaysFalse(pLeft) || exprAlwaysFalse(pRight) ){
    sqlite3ExprDelete(db, pLeft);
    sqlite3ExprDelete(db, pRight);
    return sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0);
  }else{
    return sqlite3PExpr(pParse, TK_AND, pLeft, pRight);
  }
}

int sqlite3ExprIdToTrueFalse(Expr *pExpr){
  assert( pExpr->op==TK_ID || pExpr->op==TK_STRING );
  if( !ExprHasProperty(pExpr, EP_Quoted)
   && (sqlite3StrICmp(pExpr->u.zToken, "true")==0
       || sqlite3StrICmp(pExpr->u.zToken, "false")==0)
  ){
    pExpr->op = TK_TRUEFALSE;

    return 1;
  }
  return 0;
}

/*
** The argument must be a TK_TRUEFALSE Expr node.  Return 1 if it is TRUE

      sqlite3VdbeGoto(v, dest);
      sqlite3VdbeResolveLabel(v, destIfFalse);
      break;
    }
#endif
    default: {
    default_expr:
      if( exprAlwaysTrue(pExpr) ){
        sqlite3VdbeGoto(v, dest);
      }else if( exprAlwaysFalse(pExpr) ){
        /* No-op */
      }else{
        r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
        sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0);
        VdbeCoverage(v);
        testcase( regFree1==0 );
        testcase( jumpIfNull==0 );

        sqlite3VdbeResolveLabel(v, destIfNull);
      }
      break;
    }
#endif
    default: {
    default_expr: 
      if( exprAlwaysFalse(pExpr) ){
        sqlite3VdbeGoto(v, dest);
      }else if( exprAlwaysTrue(pExpr) ){
        /* no-op */
      }else{
        r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
        sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0);
        VdbeCoverage(v);
        testcase( regFree1==0 );
        testcase( jumpIfNull==0 );

#define EP_Subquery  0x200000 /* Tree contains a TK_SELECT operator */
#define EP_Alias     0x400000 /* Is an alias for a result set column */
#define EP_Leaf      0x800000 /* Expr.pLeft, .pRight, .u.pSelect all NULL */
#define EP_WinFunc  0x1000000 /* TK_FUNCTION with Expr.y.pWin set */
#define EP_Subrtn   0x2000000 /* Uses Expr.y.sub. TK_IN, _SELECT, or _EXISTS */
#define EP_Quoted   0x4000000 /* TK_ID was originally quoted */
#define EP_Static   0x8000000 /* Held in memory not obtained from malloc() */



/*
** The EP_Propagate mask is a set of properties that automatically propagate
** upwards into parent nodes.
*/
#define EP_Propagate (EP_Collate|EP_Subquery|EP_HasFunc)

/*
** These macros can be used to test, set, or clear bits in the
** Expr.flags field.
*/
#define ExprHasProperty(E,P)     (((E)->flags&(P))!=0)
#define ExprHasAllProperty(E,P)  (((E)->flags&(P))==(P))
#define ExprSetProperty(E,P)     (E)->flags|=(P)
#define ExprClearProperty(E,P)   (E)->flags&=~(P)



/* The ExprSetVVAProperty() macro is used for Verification, Validation,
** and Accreditation only.  It works like ExprSetProperty() during VVA
** processes but is a no-op for delivery.
*/
#ifdef SQLITE_DEBUG
# define ExprSetVVAProperty(E,P)  (E)->flags|=(P)