tableblocks.cpp

我们自己写的miniSQL代码

// TableBlocks.cpp: implementation of the TableBlocks class.
//
//////////////////////////////////////////////////////////////////////

#include "TableBlocks.h"
#include "BufferManager.h"
#include "api_inte_struct.h"
#include <memory.h>
#include <string.h>

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

TableBlocks::TableBlocks()
{

}

TableBlocks::~TableBlocks()
{

}

void TableBlocks::add_table(table_info *ti,int attri_block,int record_block,int index_block)
{
	//find empty place
	int *i = new int;
	*i = 0;
	char* emptyPos = this->find_table_name((char*)i);	
	//表示找空的表名，代表没放东西的位置
	if (emptyPos == 0)
		return;

	struct tableDefinition td;
	//复制需要的内容
	memcpy(&td.table_name , &ti->table_name, 20);
	td.n_attribute = ti->n_attribute;
	td.ith_primary_key = ti->ith_primary_key;
	td.attri_start_block = attri_block;
	td.record_start_block = record_block;
	td.index_start_blcok = index_block;

	memcpy(emptyPos,&td,sizeof(td));
	// new a block for attributes
	// new a block for records
	//add info
	delete i;

}

int TableBlocks::get_attri_start_block(char *table_name)
{
	struct tableDefinition* td;
	td = (struct tableDefinition*) find_table_name(table_name);
	return td->attri_start_block;
}

int TableBlocks::get_record_start_block(char *table_name)
{
	struct tableDefinition* td;
	td = (struct tableDefinition*) find_table_name(table_name);		
	return td->record_start_block;
}

int TableBlocks::get_index_start_block(char *table_name)
{
	struct tableDefinition* td;
	td = (struct tableDefinition*) find_table_name(table_name);		
	return td->index_start_blcok;
}

// 返回该table 所在位置指针
// 传入空字符串表示找空的位置
char* TableBlocks::find_table_name(char *table_name)
{
	int i = 0;
	struct tableDefinition *td;

	while ((i+1) * ST_TABLEDEFI_SIZE < BLOCK_SIZE)
	{
		td=(struct tableDefinition *)(Block_head + i * ST_TABLEDEFI_SIZE);
		if (strcmp(td->table_name ,table_name) == 0)
			return Block_head + i * ST_TABLEDEFI_SIZE;
		
		i++;
	}
	
	return 0;
}


char* TableBlocks::get_table_info(char *table_name)
{
	struct tableDefinition* td;
	td = (struct tableDefinition*) find_table_name(table_name);		

	struct table_info* ti = new struct table_info;
	memcpy(ti->table_name , td->table_name, sizeof(td->table_name));
	ti->n_attribute = td->n_attribute;
	ti->ith_primary_key = td->ith_primary_key;

	return (char*) ti;
}