public DataBase(string name_of_file)
{
file_name = name_of_file;
file_keys = new FileKey(name_of_file);
indexes = new List<Index>();
//index = new Index(name_of_file, file_key);
}
public void ChangeIndex(int column_numb, int change_pos, FileKey file_key)
{
FileStream file;
for (int i = 0; i < file_key.keys.Count; i++)
{
file = new FileStream(file_name, FileMode.Open);
byte[] buf = new byte[file_key.keys[change_pos + 1] - file_key.keys[change_pos]];
file.Seek(file_key.keys[change_pos], SeekOrigin.Begin);
file.Read(buf, 0, buf.Length);
Record record = new Record(Encoding.UTF8.GetString(buf));
file.Close();
SetRecord(i, column_numb, change_pos, record.fields[column_numb], file_key);
change_pos++;
}
}
private void SetRecord(int record_change_pos, int column_numb, int change_pos, string record, FileKey file_key)
{
FileStream file;
if(field.Count == 0)
{
field.Add(record_change_pos);
return;
}
//
int begin_field = 0;
int end_field = field.Count;
//List<int> index = new List<int>();
// 1st one
// look for position in index
while(true)
{
int current_field = (end_field - begin_field) / 2;
// выделиьть в отдельный класс
byte[] buf = new byte[file_key.keys[field[current_field] + 1] - file_key.keys[field[current_field]]];
file = new FileStream(file_name, FileMode.Open);
file.Seek(file_key.keys[field[current_field]], SeekOrigin.Begin);
file.Read(buf, 0, buf.Length);
file.Close();
Record current_record = new Record(Encoding.UTF8.GetString(buf));
// drelete zavisaniz na evgenii
int compareResult = record.CompareTo(current_record.fields[column_numb]);
if ( compareResult<0 )
{
end_field = current_field;
if (field.Count == 2)
{
begin_field--;
}
}
else if (compareResult>0)
{
begin_field = current_field;
if (field.Count == 2)
{
begin_field++;
}
}
else
{
begin_field = end_field = current_field;
}
// if only two left -> select one
if (begin_field == end_field)
{
if (end_field == field.Count)
{
field.Add(record_change_pos);
}
else
{
field.Insert(end_field, record_change_pos);
}
break;
}
}
}
public void CreateIndex(int column_numb, FileKey file_key)
{
ChangeIndex(column_numb, 0, file_key);
}