dbcontrol.cpp

数据库模拟程序 实现控制台命令词法分析

// DBControl.cpp: implementation of the CDBControl class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "DBControl.h"


#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CDBControl::CDBControl()
{
	m_strCmd = "";
	word = 0;
	len = 0;
	
	memset(data.name, 0, 40);
	data.pDataArray = NULL;
	data.pDataArray_len = 0;
	indexArray = NULL;
	dataArray_len = 0;
	indexArray_len = 0;
}

CDBControl::~CDBControl()
{
	
}

int CDBControl::CreateTable(CString  CmdLine, Word word[], int LenOfWord)
{
	//对word 中 char float integer 的个数分别计数 为n_char,n_float,n_integer
	//!!!n_float 暂时未实现，不支持float结构
	int n_char = 0, n_integer = 0;
	
	int i = 0;
	
	if(isExistTheKey(word[2].name))
	{
		CString temp, out;
		if(strcmp(word[1].mark, "t") == 0)
			temp.Format("表 %s", word[2].name);
		else if(strcmp(word[1].mark, "v") == 0)
			temp.Format("视图 %s", word[2].name);
		else if(strcmp(word[1].mark, "x") == 0)
			temp.Format("索引 %s", word[2].name);
		else
			temp = "错误!";
		out.Format("该%s已经存在!", temp);
		AfxMessageBox(out);
		
		return false;
	}
	
	while(i < LenOfWord)
	{
		if(strcmp(word[i].mark, "a") == 0)
			n_char++;
		else if(strcmp(word[i].mark, "i") == 0)
			n_integer++;
		i++;
	}
	//m_strCmd = CmdLine;
	
	//数据项清空
	memset(data.name, 0, 40);
	if(data.pDataArray != NULL){
		delete [] data.pDataArray;
		data.pDataArray = NULL;
	}
	data.pDataArray_len = 0;
	
	//数据项赋值
	if(strlen(word[2].name) < 40)
		strcpy(data.name, word[2].name);
	else
	{
		AfxMessageBox("表名超过40个字符!请输入小于40个字符的名字!");
		return false;
	}
	
	data.pDataArray_len = n_char + n_integer;
	data.pDataArray = new DataItem[data.pDataArray_len];
	ZeroMemory(data.pDataArray, sizeof(DataItem) * data.pDataArray_len);
	
	i = 0;
	int m =0;
	while(i < data.pDataArray_len)
	{
		strcpy(data.pDataArray[i].name, word[4+m].name);
		if(strcmp(word[4+m+1].mark, "a") ==0)
		{
			data.pDataArray[i].type = 2;
			m += 3;
			data.pDataArray[i].len = atoi(word[4+m].name);
			m++;
		}
		else if(strcmp(word[4+m+1].mark, "i") ==0)
			m++;
		//		AfxMessageBox(word[4+i].name);
		m++;
		i++;
		if(m + 4 < LenOfWord)
			m++;
	}
	
	long start,len;
	len = AddToDataCiDian(data, start);
	
	
	//赋值索引变量
	IndexForCiDian index;
	strcpy(index.name, word[2].name);
	if(strcmp(word[1].mark, "t") == 0)
		index.indexType = TABLE;
	else if(strcmp(word[1].mark, "v") == 0)
		index.indexType = VIEW;
	else if(strcmp(word[1].mark, "x") == 0)
		index.indexType = INDEX;
	index.item_len = len;
	index.startOffset = start;
	
	AddToIndex_ForCiDian(index);
	
	return false;
}

int CDBControl::SelectFrom(CString  CmdLine, Word word[], int LenOfWord)
{
	return false;
}

//传递表，索引，视图的名字进来
int CDBControl::isExistTheKey(CString str)
{
	if(indexArray == NULL)
		ASSERT(initTable());
	
	int i = 0;
	while(i < indexArray_len)
	{
		if(str == indexArray[i].name)
			break;
		i++;
	}
	return ((i == indexArray_len) ? false : true);
}


int CDBControl::AddToIndex_ForCiDian(const IndexForCiDian &index)
{
	CString str;
	str.Format("%d %s %ld %ld",index.indexType, index.name, index.startOffset, index.item_len);
	fstream file;
	file.open("indexForCiDian.txt",ios::in | ios::out | ios::app);
	file.seekp(ios::end);
	if(file.write((char*)&index, sizeof(IndexForCiDian)))
		AfxMessageBox(str);
	
	file<<endl;//////////
	file.close();
	return false;
}

int CDBControl::AddToDataCiDian(const Data &dataFile, long &start)
{
	fstream file;
	file.open("CiDian.txt",ios::in | ios::out  | ios::app);
	char ch;
	while(file.read(&ch, 1))
		NULL;
	file.clear();
	
	start = file.tellp();
	
	file.write(dataFile.name, NAME_LEN);
	int i = 0;
	while(i <= dataFile.pDataArray_len - 1)
	{
		file.write((char*)&(dataFile.pDataArray[i]), sizeof(DataItem));
		i++;
	}
	long end = file.tellp();
	file<<endl;//////////
	file.close();
	return (end - start );
}

int CDBControl::initTable()
{
	ifstream file;
	file.open("IndexForCiDian.txt", ios::nocreate );
	
	if(!file)
	{//文件不存在
		ofstream fw;
		fw.open("IndexForCiDian.txt");
		fw.close();
		return true;
	}
	
	char ch;
	while(file.read(&ch,1))
		NULL;
	
	int endOfFile = file.tellg();
	file.seekg(ios::beg);
//	int index = file.tellg();
	
	
	////由于未知错误，不得不关闭文件再打开。无法在文件内部移动指针。
	////此外，移动指针为ios::end时，tellg()返回为2，是错误值。
	file.close();
	//////////////////////
	
	int count = endOfFile / sizeof(IndexForCiDian);
	
	indexArray_len = count;
	
	if(indexArray == NULL)
		indexArray = new IndexForCiDian[count];
	else
	{
		delete indexArray;
		indexArray = new IndexForCiDian[count];
	}
	
	ASSERT(indexArray);
	
	///////////
	file.open("IndexForCiDian.txt", ios::nocreate );
	////////////
	
	char buff[10];
	memset(buff, 0, 10);
	int i = 0;
	while(i < count)
	{
		if(!file.read((char*)(&(indexArray[i])), sizeof(IndexForCiDian)))
		{	
			if(!file.good())
				AfxMessageBox("文件读取错误!");
			return false;
		}
		file.read(buff, 1);
		//		AfxMessageBox(indexArray[i].name);
		i++;
	}
	file.close();
	return true;
}
void CDBControl::CheckCMD(int cmdType)
{
	switch(cmdType)
	{
	case CREATE_TABLE:
		{
			CreateTable(m_strCmd, word, len);
			break;
		}
	case DROP_TABLE:
		{
			Drop(m_strCmd, word, len);
			break;
		}
	case INSERT:
		{
			InsertIntoValue(m_strCmd, word, len);
			break;
		}
	}
}

CDBControl::CDBControl(CString str, Word *word, int len)
{
	m_strCmd = str;
	this->word = word;
	this->len = len;
	
	memset(data.name, 0, 40);
	data.pDataArray = NULL;
	data.pDataArray_len = 0;
	indexArray = NULL;
	dataArray_len = 0;
	indexArray_len = 0;
}

void CDBControl::ReadFromIndex()
{
	char ch;
	
	CString str;
	IndexForCiDian index;
	index.indexType= TABLE;
	index.item_len=0;
	memset(index.name, 0, 40);
	index.startOffset=0;
	ifstream fileIndex;

	fileIndex.open("IndexForCiDian.txt",ios::in ); 
	if(!fileIndex)
		return;
	
	
	//	Data data;
	
	while(fileIndex.read(&ch, 1))
	{
		if(ch != '\n')
			fileIndex.seekg(fileIndex.tellg() - 1);
		
		fileIndex.read((char*)&index, sizeof(IndexForCiDian));
		fileIndex.read(&ch, 1);
		str.Format("%d %s %d %d",index.indexType, index.name, index.startOffset, index.item_len);
		AfxMessageBox(str);
		str.Empty();
	}
	
	fileIndex.close();
}

int CDBControl::ReadFromIndex(long indexID, IndexForCiDian &index)
{
	ifstream file;
	file.open("IndexForCiDian.txt", ios::nocreate);
	file.seekg(0, ios::end);
	if(file.tellg() <= indexID * (sizeof(IndexForCiDian) + 2))
		return false;
	file.clear();
	file.seekg(indexID * (sizeof(IndexForCiDian) + 2));
	file.read((char*)&index, sizeof(IndexForCiDian));
	/*
	if(file.good())
		AfxMessageBox(index.name);
	else
		AfxMessageBox("Error!");
	*/
	file.close();
	return (file.good())?true:false;
}

int CDBControl::Drop(CString  CmdLine, Word word[], int LenOfWord)
{
	
	if(!isExistTheKey(word[2].name))
	{
		CString temp, out;
		if(strcmp(word[1].mark, "t") == 0)
			temp.Format("表 %s", word[2].name);
		else if(strcmp(word[1].mark, "v") == 0)
			temp.Format("视图 %s", word[2].name);
		else if(strcmp(word[1].mark, "x") == 0)
			temp.Format("索引 %s", word[2].name);
		else
			temp = "错误!";
		out.Format("该%s不存在!", temp);
		AfxMessageBox(out);
		
		return false;
	}
	
	
	if(strcmp(word[1].name, "TABLE") == 0)
	{
		
		//实现表删除
		//打开索引文件
		fstream file;
		file.open("IndexForCiDian.txt", ios::in | ios::out);
		
		IndexForCiDian index;
		strcpy(index.name, word[2].name);
		index.indexType = TABLE;
		
		CDBControl control;
		CString str;
		
		long offsetInIndex = -1;