DarkSide SQL Mini Version 1, The embedded database

/**
Copyright 2000 - 2003 LogicMatrix. All rights reserved. 

This software is distributed under the LogicMatrix Free Software License. This software may be used for any purpose, personal or commercial. Redistributions in binary /source code form are permitted. Commercial redistribution of larger works derived from, or works which bundle this software requires a "Commercial Redistribution License" which can be purchased from LogicMatrix. Contact LogicMatrix for details

Redistributions qualify as Free and non-commercial under one of the following terms:

1) Redistributions are made at no charge beyond the reasonable cost of materials and delivery.
2) Redistributions in binary/source code form must reproduce this Copyright Notice,these license terms, and the disclaimer/limitation of liability set forth as below, in the documentation and/or other materials
provided with the distribution.

Disclaimer
==========
The Software is provided on an "AS IS" basis. No warranty is
provided that the Software is free of defects, or fit for a
particular purpose. 

Limitation of Liability 
=======================
LogicMatrix shall not be liable for any damages suffered by the Licensee or any third party resulting from use of the Software.


**/

/**
select.cpp

  Purpose: Handles SELECT command
  
	Author: Vijay Mathew Pandyalakal
	Date:	16/11/2003
	Copyright: logicmatrix
**/

#include <string>
#include <vector>
using namespace std;

#include "mydate.h"
using namespace openutils;

#include "dsql_m_structs.h"
#include "bridge.h"
#include "sql_lexer.h"
#include "cmpr.h"
#include "bridge.h"
#include "rec.h"
#include "sql_utils.h"
#include "select.h"
using namespace dsqlm;

Select::Select(const char* sql,Database* db) {
	this->sql = sql;
	if(db == 0) {
		throw DsqlMException("Select.cpp - database not inited");
	}
	m_db = db;
}

void Select::setSql(const char* sql) {
	this->sql = sql;
}

ResultSet Select::parse() {
	SQLLexer lexer(sql.c_str());
	vector<string> vct = lexer.tokenize();	
	int tsz = vct.size();	
	if(tsz < 4) {
		char buff[50];
		sprintf(buff,"Invalid SELECT statement %d",tsz);
		throw DsqlMException(buff);
	}
	string s = vct[0];
	if(strcmpi(s.c_str(),"SELECT") != 0) {
		throw DsqlMException("Not a select statement");
	}
	SQLUtils utils(m_db);
	int fi = utils.findPos(vct,"FROM");
	if(fi <= 1) {
		throw DsqlMException("FROM not found where expected");
	}
	s = vct[fi+1];	
	Table table(s.c_str(),m_db);
	table.open();
	ResultSet rslt(table,m_db);
	vector<Column> vct_cols;
	s = vct[1];	
	if(s == "*") {
		int num_cols = table.getNumberOfColumns();
		for(int i=0;i<num_cols;i++) {
			vct_cols.push_back(table.getCol((i+1)));
		}
	}else {
		TokenType tt = ANY;
		for(int i=1;i<fi;i++) {
			s = vct[i].c_str();
			if(tt == ANY) {
				vct_cols.push_back(table.getCol(s.c_str()));			
				tt = COMMA;
			}else if(tt == COMMA) {
				if(s != ",") {
					throw DsqlMException("Expected comma");
				}
				tt = ANY;
			}
		}
	}
	rslt.setColumns(vct_cols);
	vct_cols.clear();
	vector<long> vct_pos;
	if(tsz == (fi+2)) { // no WHERE clause
		Rec rec(&table,m_db);
		rec.openCursor();
		long pos = 0;
		while(rec.next(&pos)) {
			if(rec.isDeleted()) {
				continue;
			}else {
				vct_pos.push_back(pos);
			}
		}
		rec.closeCursor();
	}else {
		int idx = fi+2;
		s = vct[idx];
		if(strcmpi(s.c_str(),"WHERE") != 0) {
			throw DsqlMException("Expected WHERE clause not found");
		}
		idx++;
		TokenType tt = ID;		
		vector<Column> vct_cols;
		vector<ComparissonOperator> vct_coprs; 
		vector<string> vct_vals;
		vector<LogicalOperator> vct_loprs;
		SQLUtils utils(m_db);
		for(int i=idx;i<tsz;i++) {
			s = vct[i];
			if(tt == ID) {
				Column col = table.getCol(s.c_str());
				tt = COPR;
				vct_cols.push_back(col);
			}else if(tt == COPR) {
				vct_coprs.push_back(utils.createComparissonOperator(s.c_str()));
				tt = ANY;
			}else if(tt == ANY) {
				vct_vals.push_back(s);
				tt = LOPR;
			}else if(tt == LOPR) {
				vct_loprs.push_back(utils.createLogicalOperator(s.c_str()));
				tt = ID;
			}else {
				char err_buff[50];
				sprintf(err_buff,"Unexpected token at %d",(i+1));
			}
		}
		Cmpr cmpr(&table,m_db,vct_cols,vct_coprs,vct_vals,vct_loprs);
		cmpr.run();
		long csz = cmpr.getCursorLength();
		Rec rec(&table,m_db);
		for(long k=0;k<csz;k++) {			
			if(rec.isDeleted(cmpr.getPos(k))) {
				continue;
			}
			vct_pos.push_back(cmpr.getPos(k));
		}
	}
	rslt.setCursor(vct_pos);
	rslt.setDb(this->m_db);
	return rslt;
}