SECTOR Code

#ifndef __SQL_H__
#define __SQL_H__

#include <data.h>
#include <string>
#include <list>

using namespace std;

// simple SQL semnatics
// SELECT * FROM table;
// SELECT field1, field2, ... FROM table;
// SELECT * FROM table WHERE condition;
// SELECT * FROM table1, table2, ... WHERE condition;


enum SQL_TokenType {UNKNOWN, KEYWORD, CONSTANT, ARITH_OP, BOOL_OP, MARK};
enum SQL_KeyWord {SELECT, FROM, WHERE};
enum SQL_ARITH_OP {ADD, SUB, MUL, DIV, NEG};
enum SQL_BOOL_OP {AND, OR, NOT, EQ, LT, LE, GT, GE, NE};
enum SQL_MARK {COMMA, SEMICOLON, LEFT, RIGHT};

struct SQLToken
{
   SQL_TokenType m_Type;
   union
   {
      SQL_KeyWord m_KeyWord;
      SQL_ARITH_OP m_Arith_OP;
      SQL_BOOL_OP m_Bool_OP;
      DataType m_DataType;
      SQL_MARK m_Mark;
   };
   string m_strToken;
};

struct SQLExpr
{
   vector<string> m_vstrFieldList;
   vector<string> m_vstrTableList;
   vector<SQLToken> m_Condition;
};

struct EvalTree
{
   SQLToken m_Token;
   EvalTree* m_Left;
   EvalTree* m_Right;
};

class SQLParser
{
public:
   static int parse(const string& expr, SQLExpr& sql);
   static int buildTree(vector<SQLToken>& expr, const int& start, const int& end, EvalTree* tree);

private:
   static int getToken(char** expr, SQLToken& token);
   static int validateCond(vector<SQLToken>& cond);

   static int buildArithTree(list<EvalTree*>& expr);
   static int buildBoolTree(list<EvalTree*>& expr);
};


#endif