/// <summary>
/// Unload currently loaded file. To load another file
/// it can be found with <see cref="SeekDataFile"/> and opened
/// with <see cref="LoadNextFile"/> or use <see cref="Seek"/>
/// do do it all at once.
/// </summary>
public void Unload()
{
if (this.IsDataLoaded)
{
_listReader = null;
LoadedFile = null;
}
Util.Check.Ensure(!this.IsDataLoaded);
Util.Check.Ensure(this.LoadedFile == null);
}
/// <summary>
/// Force the specified direction
/// </summary>
private void SetDirection(EnumerationDirection direction)
{
Check.Require(IsReadingSequential, StorageResources.CannotChangeReadingDirectionWhenNonSequential);
bool hadData = this.HasItem;
_direction = direction;
_timeComparison = TimeComparer.GetComparer(direction);
if (!Backwards)
{
_getFirstItemToReadFromFileName = (f) => f.FirstItemTimestamp;
_getLastItemToReadFromFileName = (f) => f.LastItemTimestamp;
}
else
{
_getFirstItemToReadFromFileName = (f) => f.LastItemTimestamp;
_getLastItemToReadFromFileName = (f) => f.FirstItemTimestamp;
}
if (IsDataLoaded && _listReader.Direction != direction)
{
_listReader = _listReader.Reverse();
Check.Ensure(_listReader.Direction == Direction);
}
int moveCount = 0;
if (IsDataLoaded)
{
// in sequential mode and when data is loaded iterator points to the data file to load next, so need to move by 2
// (skipping currently loaded file)
moveCount = 2;
}
else
{
// data is not loaded; 2 cases: 1) seek found file with data beyond seek time and 2) seek time is contained in the file
if (!NextFileFound || IsNextFileToBeReadInFull)
{
// case 1
moveCount = 1;
}
// case 2: next file remains valid because will have to read some data from it in the opposite direction
}
_fileIterator.Backwards = Backwards;
for (int n = 0; n < moveCount; ++n)
{
MoveIteratorToNextFile();
}
if (!hadData)
{
_position.SetEmpty(direction);
}
}
/// <summary>
/// Loads the specified file and positions at the first data item.
/// </summary>
/// <exception cref="System.IO.FileNotFoundException">
/// The <paramref name="dataFile"/> does not exist on disk.
/// </exception>
private void ReadFile(IRepositoryFile dataFile)
{
// passing null for equally timestamped items comparer, data items are read in the same
// order as they were written; no sorting when reading by design
IDataFileAccessor accessor = GetAccessor(dataFile);
// will throw exception if file not found or failed to read
accessor.ReadFromFile();
IList <IDataItem> dataList = accessor.GetAllItems();
if (Backwards)
{
_listReader = new BackwardListReader <IDataItem>(dataList);
}
else
{
_listReader = new ForwardListReader <IDataItem>(dataList);
}
this.LoadedFile = dataFile;
Check.Ensure(_listReader.HasItem);
Check.Ensure(CurrentItem != null);
}