/// <summary>
/// Loads meta information into this instance of <see cref="RecordStream"/>.
/// If you have called <c>UnloadInfo</c>,
/// the status of this <see cref="RecordStream"/> instance will be restored where it was right before the last time UnloadInfo was called.
/// </summary>
public virtual void LoadInfo()
{
//reads info from <paramref name="infoStream" />
if (_rinfo != null)
{
return;
}
if (_infoPos >= 0)
{
_infoStream.SeekTo(_infoPos);
if (_infoStream.Check(IOChecks.RecordStream))
{
_rinfo = new _rinfo();
_rinfo._metaNum = _infoStream.ReadInt32();
_metaNumRetrieved = true;
_rinfo._blockLength = _infoStream.ReadInt32();
_rinfo._totalLength = _infoStream.ReadInt64();
if (ReadMoreInfo != null)
{
ReadMoreInfo(_infoStream);
}
_rinfo._list = new List <long>();
_infoStream.ReadList(_rinfo._list);
}
else
{
throw new InvalidDataException(IOResources.ERR_StreamExtension_DataIrrecognizable);
}
}
}
/// <summary>
/// Unloads the meta information of this <see cref="RecordStream"/> instance and release some memory.
/// Before calling this method, you must make a decision to save or discard the changes to the data blocks.
/// Later you are able to reload the meta information by calling LoadInfo again.
/// </summary>
public virtual void UnloadInfo()
{
if (_rinfo == null)
{
throw new InvalidOperationException(IOResources.ERR_IRecord_NotLoaded);
}
if (_rinfo._infoModified1)
{
throw new InvalidOperationException(IOResources.ERR_RecordStream_UpdateNotSaved);
}
if (_rinfo._list != null)
{
_rinfo._list.Clear();
_rinfo._list = null;
}
_rinfo = null;
}
/// <summary>
/// Makes this <see cref="RecordStream"/> represent a new record without eliminating the data
/// of the previous record in the underlying stream.
/// If you have already loaded an existing record into this instance and made changes to the data blocks,
/// and you call this method again before you call <c>SaveInfo</c>, and then these new changes will be lost.
/// </summary>
/// <param name="blockLength">The length of each data block in this record stream.</param>
public void CreateNew(int blockLength)
{
if (blockLength <= 0)
{
throw new ArgumentOutOfRangeException("blockLength", GeneralResources.ERR_PositiveValueRequired.Scan("blockLength"));
}
if (_infoPos == -1 && _rinfo == null)
{
_rinfo = new _rinfo();
_rinfo._list = new List <long>();
_rinfo._totalLength = 0;
_rinfo._blockLength = blockLength;
_currPos = -1;
_rinfo._infoModified1 = true;
_rinfo._infoModified2 = true;
}
else
{
throw new InvalidOperationException(IOResources.ERR_RecordStream_InvalidCreation);
}
}