include/Expression.h

   1 /***************************************************************************
   2  *   Copyright (C) 2007 by www.databasecache.com                           *
   3  *   Contact: praba_tuty@databasecache.com                                 *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  ***************************************************************************/
  16 #ifndef EXPRESSION_H
  17 #define EXPRESSION_H
  18 #include<os.h>
  19 #include<DataType.h>
  20
  21 class Table;
  22 class TableImpl;
  23
  24 enum ArithOperator {
  25     unKnownOperator = 0,
  26     addition,
  27     subtraction,
  28     multiplication,
  29     division,
  30     modulus
  31 };
  32 class Expression
  33 {
  34     char fldName[IDENTIFIER_LENGTH];
  35     void *tuple;
  36     void *constVal;
  37     void *calVal;
  38     TableImpl *table;
  39     ArithOperator arOp;
  40     Expression *lhs;
  41     Expression *rhs;
  42     public:
  43     Expression()
  44     {
  45         table=NULL; arOp = unKnownOperator; lhs=NULL; rhs=NULL;
  46         tuple=NULL; constVal=NULL;
  47         strcpy(fldName,"\0");
  48     }
  49     ~Expression()
  50     {
  51         if(lhs){ delete lhs; lhs=NULL;}
  52         if(rhs){ delete rhs; rhs=NULL;}
  53     }
  54     void setTable(Table *tbl);
  55     void setTuple(void *tpl);
  56     bool isSingleTerm();
  57     void setExpr(char const *name,ArithOperator op,void *cVal );
  58     void setExpr(char const *name);
  59     void setExpr(Expression *exp1, ArithOperator op, Expression *exp2 );
  60     void setExpr(void *cVal,bool flag );
  61     void *evaluate(DataType type,bool &result);
  62     void solve(void *opand1, void *opand2, DataType type, ArithOperator arOp);
  63     void convertStrToVal(DataType type);
  64     void freeVal();
  65     void memFree();
  66 };
  67
  68 #endif