public VirtualMemory(string filePath, int pageCapacity, int pageNumber, bool overwrite = true, IIntConverter intConverter = null, IBoolConverter boolConverter = null, IStringConverter stringConverter = null)
{
var simpleConverter = new SimpleConverter();
_intConverter = intConverter ?? simpleConverter;
_boolConverter = boolConverter ?? simpleConverter;
_stringConverter = stringConverter ?? simpleConverter;
_markerSize = _stringConverter.ToBytes(_marker).Length;
var exist = !overwrite && File.Exists(filePath);
_memoryFile = new FileStream(filePath, overwrite ? FileMode.Create : FileMode.OpenOrCreate, FileAccess.ReadWrite);
_memoryFile.Seek(0, SeekOrigin.Begin);
_br = new BinaryReader(_memoryFile);
_bw = new BinaryWriter(_memoryFile);
PageCapacity = pageCapacity;
PageNumber = pageNumber;
if (exist)
{
var marker = Encoding.Unicode.GetString(_br.ReadBytes(_markerSize));
var tempCapacity = _intConverter.ToInt(_br.ReadBytes(_intConverter.IntSize));
var tempNumber = _intConverter.ToInt(_br.ReadBytes(_intConverter.IntSize));
if (marker != _marker || tempCapacity != pageCapacity || tempNumber != pageNumber)
{
throw new FileLoadException();
}
LoadPage(0);
}
else
{
CurrentPage = new MemoryPage(0, PageCapacity);
_bw.Write(_stringConverter.ToBytes(_marker));
_bw.Write(_intConverter.ToBytes(PageCapacity));
_bw.Write(_intConverter.ToBytes(PageNumber));
for (int i = 0; i < PageNumber; i++)
{
WritePage(i);
}
}
}
private void LoadPage(int number)
{
_memoryFile.Seek(_markerSize + _intConverter.IntSize * 2 + (_boolConverter.BoolSize + _intConverter.IntSize) * PageCapacity * number, SeekOrigin.Begin);
var map = new bool[PageCapacity];
var val = new int[PageCapacity];
map = map.Select(x => _boolConverter.ToBool(_br.ReadBytes(_boolConverter.BoolSize))).ToArray();
val = val.Select(x => _intConverter.ToInt(_br.ReadBytes(_intConverter.IntSize))).ToArray();
CurrentPage = new MemoryPage(number, map, val);
}